If you shooting one colour then you can scuff up the body lightly then wash it out this will give the paint a key to stick to.
From my experience it seems like you have just put the coats on a little thick, it happens
The heat from a hair dryer is enough to dry between coats and doesn't effect the paint sticking. Also I never use to bother washing the body with single colours (never had any problems) tho it does make good practice to do it!
Also Fastrax and tamiya aren't the same and I personally feel the tamiya stuff tho a little more costly is much better.