Aluminun is a special situation when it comes to painting regular paint will not stay stuck to aluminum and will come off it requires a special primer called Zinc Chromate which if you can find it is expensive, however you can easily get around having to use it if you acid etch the metal, OOOH sounds serious, not really get a clean spray bottle like one that windex comes in and fill it with White Vinegar, vinegar is a mild acid and is just enough to etch the metal, spray the surfaces you're going to paint keep the surfaces wet with the vinegar refreshing the spray for about an hour, then wash the surfaces with warm to hot water, no soap the vinegar will wash right off, the metal surface will change from a shiny to a satiny sheen, once its completely dry, prime the metal with any Lacquer based automotive primer, don't get in a hurry at this point take your time light multiple passes with the spray paint, not heavy coats, then finish coat after about 2 hours with a Lacquer based finish paint like Krylon. It will work just fine. Remember to take your time during the painting and use multiple light coats until you've achieved the finish you're after, its better to buy more paint than you need, and do some test shooting on some scrap metal, to find out for yourself how much is too much, so you don't get any runs. Good luck with your paint project.
Yes you can use the same laquer based paints on plastic surfaces because it will dry before it can damage the surface, just make sure on plastic that you use something like denatured alcohol to remove fingerprints and grease off of the surface before you paint it, and if you have to sand anything at all do not sand the plastic. The laquer will bond to it just the way it is, use masking tape to cover the things you don't want painted like your LED lights on the CDROM drive and such as that.