Welcome, Drew! Thanks for coming back
It sounds as though you're wanting to take almost the same path I did... and this thread pretty well chronicles my trip.
First, RC aircraft... initially I introduced the needle cutter out on the RCPowers forum... which, sadly, no longer exists. I chose that venue because the needle cutter and their "score, cut, and fold" technology seemed a great "marriage" that yielded some really nice looking planes.
Shortly thereafter, I introduced it to the FliteTest and RCGroups forums... and ultimately the FT forum is the one that really generated interest and took off. My very first post in this thread shows a couple of those RCPowers planes (F-117 and Mig-29)... along with a scaled-down FT Old Fogey, a T-rex for the grandson, examples of the DTFB cut quality, and the MPCNC I was using at the time. So, the CNC machine doesn't care whether the parts it's producing are RC planes, dinosaurs, or architectural pieces... I think we've got you're covered.
Early on, I also used the needle-cutter to cut 3mm cardboard. Check out post #907... the stegasaurus on the placemat was needle-cut. But cutting cardboard was a torture-test of sorts... it readily cut through in a single pass but an Xacto blade had to be used in places on the bottom-side to fully extract the parts. I've intended for a long time to revisit those efforts... possibly making multiple passes can improve the result.
In that same post #907, you'll see a tiny triceratops laser-cut from cereal-box cardboard (chipboard?). Shaky as I am, I put only the head together -- using tweezers to pick up and place the parts -- but I was impressed with the precision I could now get. Miniatures are not my thing but the laser is the way to go for that kind of stuff.
So, there you have it. Unless you have a 40+ watt CO2 laser -- and I don't -- papered foam is IMHO best cut with a needle-cutter... inexpensive, great detail, straight-sided cuts (no under-cutting), little/no debris generated, etc. With cardboard and chipboard, larger pieces can be needle-cut somewhat successfully but a laser is IMHO far preferable, especially for miniatures. Even a modest diode laser is a great addition to the arsenal... with patience, it can cut many materials -- sadly, not white DTFB -- but it also engraves many materials beautifully.
Finally, MPCNC is a great choice for those first steps into the world of CNC... relatively inexpensive, flexible sizing/tooling, fun and incredibly educational to build, etc. In short, it is a DIYer's dream and pretty much why this thread is so eclectic... without the flexibility MPCNC affords, much, if not most, of this stuff I would have never attempted.
There's so much more to talk about but we can save that for later. Virtually everything you mentioned can be, and has been, done... much of it routinely. And, one of the greatest attributes of automation, the time spent preparing the work for machine operations, is recouped in spades when you start making copies.
Again, welcome to the party, Drew.
-- David