I just found this thread, I didn't even know we had an airbrush board. (Edit: whoops, I thought I was on a different board that uses this same design. I'm a regular there, still a newb here). Thanks for doing this, I've been selling airbrushes and helping folks use them in a hobby shop for 14 years and you're going through the same things that every airbrush beginner goes through. But you're doing one main thing correct - you're using it! Too many people give up at the first sign of trouble. I'm going to start pointing folks to this thread.
Here's a free Terry Hill video that talks about airbrush troubleshooting. I've only skimmed it, so I'm not sure how much of it applies to modelling and how much applies only to t-shirt painting, but since airbrushes are the same it should be helpful.
I would recommend getting a spray booth at some point. I bought mine from Amazon for around $100.