SOLVED SOLVED SOLVED

First... what a KICK ASS community - ya'll came to help a n00b quickly - provided good advice and examples

1. Extruder Temperature reset to 0 when print started
   Cause: these three lines in the printer profile from Cura

M104 S[extruder0_temperature] 
M109 S[extruder0_temperature] 
M109 R[extruder0_temperature] 

**Fix - Comment them out. **
changing [ and ] to { and } didn't help

2. Part cooler fan not on at beginning of print
   Cura had a deep setting under cooling for first layer fan % - it was set a zero - this put a fan off command (M107) right before the print started... caused problems. Change that setting to non-zero.

3. Changed title of this thread for next guy who Duets his Tornado and uses Cura. It's working like it should now and I don't have to fiddle with anything before I send prints. I have completed the Duet Tevo Tornado Cura transition. (I tried to put "solved" in the main thread title and it got flagged as spam).

4. Thank you folks in this thread for the help!

SOLVED SOLVED SOLVED

First... what a KICK ASS community - ya'll came to help a n00b quickly - provided good advice and examples

1. Extruder Temperature reset to 0 when print started
   Cause: these three lines in the printer profile from Cura

M104 S[extruder0_temperature] 
M109 S[extruder0_temperature] 
M109 R[extruder0_temperature] 

**Fix - Comment them out. **
changing [ and ] to { and } didn't help

2. Part cooler fan not on at beginning of print
   Cura had a deep setting under cooling for first layer fan % - it was set a zero - this put a fan off command (M107) right before the print started... caused problems. Change that setting to non-zero.

3. Changed title of this thread for next guy who Duets his Tornado and uses Cura. It's working like it should now and I don't have to fiddle with anything before I send prints. I have completed the Duet Tevo Tornado Cura transition. (I tried to put "solved" in the main thread title and it got flagged as spam).

4. Thank you folks in this thread for the help!

@dc42

;Generated with Cura_SteamEngine 3.5.0
M140 S60
M105
M190 S60
M104 S210
M105
M109 S210
M82 ;absolute extrusion mode
; start_gcode
M117 Start Clean        ; Indicate nozzle clean in progress on LCD
;
M104 S[extruder0_temperature] 
M109 S[extruder0_temperature] 
M109 R[extruder0_temperature] 
;
M107                    ; Turn layer fan off
G21                     ; Set to metric [change to G20 if you want Imperial]
G90                     ; Force coordinates to be absolute relative to the origin
G28                     ; Home X/Y/Z axis
;
G1 X3 Y1 Z15 F9000      ; Move safe Z height to shear strings
G0 X1 Y1 Z0.2 F9000     ; Move in 1mm from edge and up [z] 0.2mm
G92 E0                  ; Set extruder to [0] zero
G1 X100 E12 F500        ; Extrude 30mm filiment along X axis 100mm long to prime and clean the nozzle
G92 E0                  ; Reset extruder to [0] zero end of cleaning run
G1 E-1 F500             ; Retract filiment by 1 mm to reduce string effect
G1 X180 F4000           ; quick wipe away from the filament line / purge
M117 End Clean          ; Indicate nozzle clean in progress on LCD
;
M117 Printing...
; Begin printing with sliced GCode after here
;
G92 E0
G1 F2400 E-6.8
;LAYER_COUNT:121
;LAYER:0
M107
G0 F3600 X111.728 Y131.083 Z0.2
;TYPE:SUPPORT
G1 F2400 E0
G1 F1500 X112.003 Y130.851 E0.01197
G1 X112.184 Y130.711 E0.01958
G1 X112.425 Y130.56 E0.02904
G1 X112.757 Y130.385 E0.04152

M107 ; Turn layer fan off <-- that looks like the problem
shutting off the part cooling fan

**M104 S[extruder0_temperature]
M109 S[extruder0_temperature]
M109 R[extruder0_temperature] **
this block appears to hold the issue?

Thank you for the responses.
I followed the suggestion from Phaedrux. The behavior did not change. After the hot end reaches temperature (after the print command is given).... it resents to 0 and cools down and fails.

; Configuration file for Duet WiFi (firmware version 1.21)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v2 on Wed Feb 06 2019 19:48:45 GMT-0800 (Pacific Standard Time)

; General preferences
G90                                                ; Send absolute coordinates...
M83                                                ; ...but relative extruder moves

; Network
M550 P"Tornado"                                    ; Set machine name
M552 S1                                            ; Enable network
M587 S"xxxxxx"          ; Configure access point. You can delete this line once connected
M586 P0 S1                                         ; Enable HTTP
M586 P1 S1                                         ; Enable FTP
M586 P2 S1                                         ; Enable Telnet

; Drives
M569 P0 S0                                         ; Drive 0 goes backwards
M569 P1 S0                                         ; Drive 1 goes backwards
M569 P2 S1                                         ; Drive 2 goes forwards
M569 P3 S1                                         ; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1                            ; Configure microstepping with interpolation
M92 X80.00 Y80.00 Z400.00 E400.00                  ; Set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00                ; Set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z6000.00 E1200.00           ; Set maximum speeds (mm/min)
M201 X200.00 Y200.00 Z100.00 E250.00               ; Set accelerations (mm/s^2)
M906 X800.00 Y800.00 Z800.00 E800.00 I30           ; Set motor currents (mA) and motor idle factor in per cent
M84 S30                                            ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1                                   ; Set axis minima
M208 X300 Y300 Z400 S0                             ; Set axis maxima

; Endstops
M574 X1 Y1 Z1 S0                                   ; Set active low and disabled endstops

; Z-Probe
M558 P0 H5 F120 T6000                              ; Disable Z probe but set dive height, probe speed and travel speed
M557 X15:285 Y15:285 S20                           ; Define mesh grid

; Heaters
M305 P0 T100000 B4138 R4700                        ; Set thermistor + ADC parameters for heater 0
M143 H0 S120                                       ; Set temperature limit for heater 0 to 120C
M305 P1 T100000 B4138 R4700                        ; Set thermistor + ADC parameters for heater 1
M143 H1 S265                                       ; Set temperature limit for heater 1 to 265C

; Fans
M106 P0 S0.3 I0 F500 H-1                           ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H1 T45                        ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
;M106 P2 S1 I0 F500 H0:1 T45                        ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is ;turned on

; Tools
M563 P0 D0 H1                                      ; Define tool 0
G10 P0 X0 Y0 Z0                                    ; Set tool 0 axis offsets
G10 P0 R0 S0                                       ; Set initial tool 0 active and standby temperatures to 0C

; Automatic power saving
M911 S10 R12 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; Set voltage thresholds and actions to run on power loss

; Custom settings are not configured

; Miscellaneous
M501                                               ; Load saved parameters from non-volatile memory

Have a Duet Wifi that I put on a Tevo Tornado.
(why? I don't have a good reason)
Wired up correctly (everything works up to a point).
used this guide and config file, all settings make sense to me and all controls from the GUI work as they should.

I can give advice on all the rewiring that needs done in this transition.. it is quite a big project, but not hard.

fan0 (part cooler) ON all the time (by design I believe)
fan1 ( hot end cooler) thermostatically controlled.

fan test - fan0 works as the test says, fan1 never comes ON

give it something to print --> starts normally... then
it gives the message:
warning: Tool 0 was not driven because its heater temperatures were not high enough or it has a heater fault

... and so the nozzle heater quits and the print fails as it cools down, ALSO, after it transitions to print - the default ON part cooler fan goes OFF (then comes back on after you quit the print, and stays on during all non-printing times).

A picture of the evolution.

Thank you in advance for any advice.
UPDATE = I did notice the fan at 0% in the picture... so I went and manually adjusted... now realizing what is happening is that hot end temperature setting and part cooling fan setting are somehow getting clobbered to 0 when print command given... the fan is set to 0 immediately and the hot end changes to 0 after it reaches the setpoint to print and starts to print. I immedately reset them to the desired settings and the error message did not come in.... so it looks to be more of a setting preservation issue as the error code was probably triggering from the change in hot end temperature?