I can’t answer everything because I don’t make models myself, but don’t buy a 3D printer. Getting it set up and calibrated takes ages, as well as the learning curve. Find a service online, you send them your file and they print it and send it back. PLA is the most common material for printing and I expect it would be fine here, I haven’t really used anything else and I have no problems. You can just make the plastic thicker to make it stronger.

The painting part should be fine but you’ll probably have to use a primer. Get a few prints so you can make mistakes.

Just find an online printing service and they should be able to answer a lot of your questions.