@Ak:
Only one question (right now): Is there any reason to get the whole kit built hooked up to the MSKBase first… or should I skip all that and just hook up the Duet directly? I ask because I haven't actually purchased the DuetEthernet yet. If I'll save a bunch of time going that route directly (straight to Duet), the I may as well order now so it's all ready to go at the same time…
No good reason that I could think of, aside from using it to verify that none of the parts are faulty.
What you could do in advance is modifying or swapping the connectors for compatibility with the Duet. I went the "modify" route and used side cutters and a precision knife to peel off plastic fins off the motor connectors and elsewhere where they would cause the white plastic back wall on the Duet board connectors to bend. I also replaced or split some Dupont connectors (e.g. BLTouch 1x3pin and 1x2pin to 3x1pin and 2x1pin). Be sure to at least check the wiring, as some of my kit's Dupont connectors had pretty awful crimping applied…
Be extra-attentive with the SSR (enclosed in the big black box on top, together with the PSU), and remember to generate your own PID for the hotend (and preferably the heated bed, although I skipped tuning that and just used OP's values which seem to work for me).
EDIT: You probably know, but just in case... Remember that the frame is grounded via the screwed connection to the aforementioned black aluminum case containing the PSU and SSR, so if you ever decide to relocate the PSU you have to remember to pull your own wiring from the PSU's protective earth connectors to the frame and check with a multimeter that the separate parts of the whole structure are grounded, with the most important part of course being the aluminum around and beneath the mains-powered heated bed. Checking that these parts are properly grounded is smart even if you modify nothing. I would go as far as making certain that the PSU's protective earth is in fact connected to proper pin on the back of the enclosure where the power cord is connected, and use a power cord that definitely isn't defective.