Grab the yellow pages, or do a net search for painters + your city. You can try powdercoating too. Powdercoat gives a strong coat that don't chip easily. Beware that for a good result all the components has to be removed from the frame, and the frame has to be prepped(sanded, media blasted, cleaned...), and this will cost you some.
DIY rattle can paint jobs rarely get as strong as professional paint jobs, which means paint that chips and take scratches easily - not what you want for a BMX
At home - with great difficulty. In a factory - reasonably easy. Tubing for frame is cut to length and joined. Frame is painted, then the bike is assembled.
A BMX stem is what connects the handlebars and forks to the frame.
The frame
Unbolt everything from old frame, assemble on new frame, done.
6
Sunday funday
Roughly 5 lbs.
All "true" BMX bikes are built for 20" wheels, which makes them very similar in size.
You can remove bearings from a BMX frame with a 'mid' bottom bracket without damaging them using a 3/8s rachet extension.
Depends on the bike frame..
uhhm the only thing i would say its that if you want to keep your frame, stop doing that. if your frame becomes damaged, you should replace it. if theres a worn down part of the frame, it will be a point that can fracture from the stresses of BMX riding because it will be weaker than the surrounding areas on the frame.
No. A BMX is almost entirely ridden "out of the saddle" (=standing up), so size doesn't mean that much. (most) MTBs are intended for some seated riding, which makes frame size much more important.