Welcome
Most of your questions have been covered here before and will already be listed in either the FAQ, How To section or on
http://www.Scalewiki.com
As for bottles and cans of paint, they will need to be thinned for airbrushing, this isn't difficult and is, once again, a topic covered here frequently.
Recommendations of either Badger, Paasche or Iwata airbrushes are right on, they're good brands and a few more dollars spent now will be some money you don't have to part with at a later date.
Ray