My words of wisdom:
Cheap paint is just that, cheap paint. Get the Best latex you can for around $20-25 bucks a gallon.
It isnt just that the warranty is crappy. It is harder to work with, usually thinner, more runs, drips, errors, have to do more coats.
It is easier to paint over a dark color than a light color.
Get good rollers and brushes. Clean them well when you are through and they will last.
If you cant paint it all in one sitting get some cling wrap (or a ziplock bag, or even a good plastic shopping bag) and totally cover the brushes and rollers making sure no air can get to it. You can leave this out for lunch like this, or toss it in the refrig over night.
A gallon of paint should do a 10-12 x 10-12 room (if you have 8' ceilings)
With good Latex paints you can put it on VERY thick, this is good.
Surface prep is the key to everything though. You can make cheap paint over a properly prepared surface look better than the BEST paint over a ill-prepared surface. PAtch the surface, sand the surface (especially if the paint up is a 'gloss' type, you HAVE to rough up gloss (anylevel of gloss, not just 'shiny) with a quick fine grit sandpaper), wash the surface, prime the surface (if necessary, if you already have good paint that was correctly applied then priming isnt really necessary), then paint.
Have fun, put on the tunes, remember you can always repaint later.....