Also, what is the best length of time to wait between coats? I was waiting an hour.
If you're using enamel paint, I've always had the best results waiting 20-30 minutes in between coats. Much more than that could cause you to have some issues like you were experiencing this last time. If you are using lacquer, usually only about 10 minutes between coats, if that. I've read where guys just let lacquer dry to the touch, and shoot it again. Personally, I use the 10-15 minute time period for lacquer coats.
As the others have stated, your prep is very important as well. There are varying but good methods that are used by the others, and they all should work well. Priming your model is a very good idea, if you haven't been doing that. I usually use 320-400 grit for bodywork, but around 600-1000 grit after initial mold lines and putty sanding is done, and after priming.
I have always stayed about 10-12 inches from my subject when shooting as well. Much more than that cuases me to get a very orange peel paint job, that takes a lot of work to get looking better. Sometimes I've even had to strip and repaint due to too much orange peel.
Your bubbles in the paint probably was due to the solvent in the paint getting trapped under too thick of paint. It's trying to "escape", but can't get through the thick paint quickly enough before the top layer starts to dry. I have seen this happen with enamels in particular, and mostly it's where the paint gathers around the wheel opening lips and bottom of the model. Rocker panels in particular. Temperature, humidity, and wind play a big role in this particular process, especially being outside.
I have had similar problems in the past, like you experienced painting outdoors. If you can do it, paint indoors where there is no chance of getting the breeze effecting your paint job. It doesn't take much to mess things up, as you've discovered!
Krylon is good paint, Mark. You should really prime under it though. I have to agree with Ed on the Testors primer. Unless you get some in the Model Master lacquer line, it is just flat gray enamel paint! I also agree with John about the Tamiya primer. It's some of the best for model building. The biggest drawback to it, is the price. It's quite expensive quantity-wise, compared to say a Duplicolor or Krylon primer (which I like quite well also). Hope this helps ya out a little.