spray painting bikes

[yeehawfactor]

i borrowed a beater(1993 diamondback) from the LBS here at school to use as an interim cruiser. since it's early in the semester, i'm pretty bored(and not big into substance abuse), so i called and received permission to paint it. i went to lowes, got the brightest orange spray paint i could find, made flame stencils, and hit the fork and headtube. i did nothing to prep the existing paint. after the orange dried, i removed the stencils to find that paint had collected around the tape that was on the back of the stencils to hold them in place. so there is paint where there shouldn't be under the stencil. my questions are:

1. what materials should i use as stencils and how should said stencils be affixed
2. how should i have prepped the existing paint
3. any advice on spray painting methods(i.e. lots of light coats, a few heavier coats, etc)
4. is there anything more awesome to stencil than flames?
5. why was i scared of the uber-euro t-mobile-esque bright pink?

thanks!