I'll tell you the little i know (feel free to set me straight if anyone knows better). There are two main types of etch primer, acid etch, which physically 'burns' into the surface you spray it on, and another type, which adheres by sending 'hook like spores' into the surface it is sprayed onto. Obviously, they stick to the base metal real well, so resist stone chips etc.
Two pack paint, basically means you get two packs (tins) when you buy the paint. The paint itself, and the activator/thinners, which you mix together, the two react which drys the paint. 2 pack dries quicker and harder than single pack (aerosoles/cellulose, which dry by evaporation) ,which make it better suited for your application. Though, 2 pack paints are carcinogenic, so your supposed to have full respiratory equipment, and extraction facilities etc to protect yourself, and others, when using it.
The equipment you need to apply 2 pack, is the same as for single pack. A compressor, regulator and water trap, and a spray gun. If your gonna have a go, practise on something thats scrap or unimportant first to build your confidence. As if you get any runs, their a b*tch to flat out, because the paint drys hard!
Try 'Frost Restoration Equipment' for the 'Clean n strip disks' (web wheels), WWW.FROST.CO.UK or get them from 'RS Components Ltd', their about a third of the price of 'Frost', but you'll need a trade account for them.