All good information, and I too have learned a lot from FSM and various books on the subject... but answering those three questions directly...
1)Patching - You can use putty if you would like. There are a wide variety availible at the hobby store. My personall favorite is Squadron Green Putty. However, I prefer to use gap filling super glue to fill in small hole and dips. I use Zap-A-Gap with and accelerator and sand it immediately (if you use accelerator you only have about half an hour or so before it become very had to sand and doesn't work as well, so work in small sections).
2)Painting without an airbrush - It has been a while for me, but it really comes down to how pretty you want it to look. You can buy the cheap airbrishes (I don't recommend it)... you can try regullar paint brushes to. The best way to get results is to put the paint on lightly. Don't lay it on thick, just because you can still see color from below. Build it up over several coats if colors show through, but let there be a good day or two between coats. But the simplest way to get nice (but no great) finishes is to use spray paint. When I was a kid, I even sprayed my kits before build, just because it was easier, and they usually look good enough. You won't get professional quality with either method... but no need to rush things, move to an air brush when you are comfortable.
3) Cockpit detail - This realy comes down to the scale and the kit. In 1/72, if the kit has raised details try painting the control pannels black or dark grey and then, later, go over them lightly with a brush using a lighter grey or white (dry brushing)...or you could just get a very fine brish and pend a lot of time straining your eyes marking each nob. If the kit has no raised details...they should come with decals and that may be your best bet until you gain some experience in scratch building. For 1/48 or larger, the methods can be the same, but it is easier to paint diferent colors on the various nubs and switches. You can add your own with some streched sprue peices, fine plastic rods, pins, sheet styrene, or anything else that works. The last thing I will mention is seat belts. A difficult thing to master, but if you want good looking seat belts quick and easy, just get some tan masking tape and cut it to size. Stick it where the belts go and maybe paint some buckles on to at detail. That should work for most beginners.
Hope that more directly answers you questions!