Turntables from the quad era are likely to have the appropriate low-capacitance for cd-4, modern ones can work too, I'm not sure which exact models. There are multiple carts/styli options for cd-4 but they are not cheap, here is one thread(of many) on this subject:
https://www.quadraphonicquad.com/forums/threads/new-to-quad-which-cd-4-cartridge.28338/
Not exactly, if you are using a standalone demodulator, the turntable will be directly connected to the demodulator and then the 4 channels from the demodulator go to the amp(s)/tape monitor. Here is another thread which this was recently discussed:
https://www.quadraphonicquad.com/forums/threads/marantz-cd-400-stopped-working.29613/
"Quadradisc"=CD-4, Dynagroove=not quad, Duophonic=fake stereo, "35mm film vinyl" is Enoch Light(quad format can vary), not sure about the others. Oddly enough, "phase 4" was also being discussed the other day on this thread:
https://www.quadraphonicquad.com/forums/threads/pye-594-4ch-stereo.29648/