Heya Talem,
Ok I'll stick to modleing to help you out. You will not need more then 25-30 psi MAx, most of your model ABing will be around 15-20 psi. 25-30 psi to clean with. With an oiless or diaphram compressor, often called a hobby compressor youll need a air regulator and moisture trap. You air will be coming to your AB directly from the compressor in really fast pulses. If you find that idea bad(I use a testors mini blue myself)then there are small hobby compressor that have a small tank installed with them. Aztek makes a decent one, top notch would be Badger millenium or an Iwata(media) comp.
Only thing the airtank does is give you a continious steady air. You take from the airtank and the compressor fills the airtank back up. In the long run the vast majority of modelers will use a tank equipped compressor.
Hope this helps you out and points you in the right direction,
Jeff