Agree with CBR6DC, spray cans are good enough for a track bike (if you drop it regularly
) and they save you the trouble/expense of kitting up to use 2 pack or whatever.
BUT if you do want a harder wearing finish...the most important thing to remember if you use 2-pack is to get a forced air mask, or a proper organic filtered face mask if that's too expensive - I prefer the air fed ones because the saturation time on standard filters is pretty quick. Don't stick one of those dust mask things on, this paint is lethal in relatively low concentrations. Sorry if that's teaching you to suck eggs, but I'd rather tell you stuff you know already than not mention it at all
Cost wise, you're looking round about £20 a litre for decent 2-pack, £20/l for etch primer,£8-9/l for hardener & thinner, and probably £15 for clear lacquer (which you can live without if you're not using metallic color). Most suppliers will sell you half litres, so adjust price accordingly. Pick a hardener according to how fast you want the paint to dry, they're graded as fast,normal or slow, so no prizes for guessing what each type does...If you don't have infrared heaters, slow probably isn't a good idea as it'll increase the amount of time for your paint job to gather fly cr*p and all the other natural goodness floating around in the air.
I generally recommend etch primer as it just seems to stick better to plastics than any of the dedicated plastic primers I've tried. You can buy the U-Pol spray cans for 12-15 a go, and as you don't need a lot that might be the way to go.
Stickers generally come of with a paint gun as they're only vinyl, so after stripping them just rub down with medium grade paper (600 grade is what I generally use on ungouged paintwork), then adjust this keying surface according to how much build you want from the primer. I usually lightly sand (800 -1000 grit)if I'm not covering too many scratches etc.
Always wipe down with panel degreasant/lint free cloth before spraying (yet more expense!), it does make a big difference to adhesion. Mix Primer/paint with hardener 1:3 or 1:4 and adjust the viscosity with thinner (about the same price as Hardener) up to about 20-25% before spraying. For acid etch primer, start with a very light first pass - almost a 'dusting' - as it'll greatly reduce the chance of runs. repeat as necessary. I usuallykey the primer with 1000-1200 grit paper then degrease before top coating - same 'first dusting' principle has worked well for me with topcoat as well.
Note: you get 10-15 minutes with normal hardener before your spraygun turns to a block of solid pigment. Worth remembering, bitter experience speaks