Since all knowledge is now available on the 'net
and it's been soooooo long since I dabbled in the sparky world, I thought I'd have a quick (and short) go at this. Hopefully others with more (and more recent) experience can jump in.
Assuming you're talking about a standard full wave bridge rectified PS, and not a switcher... here's one pointer to some basics on cap values for amps
http://sound.westhost.com/power-supplies.htm. But like a lot of the old electronics books it uses some generalities (you'll notice they get the cap sizing formula from a rectifier data book... which tend to stay in the "simple" realm). But it hits some of the other points needed for a good design... the components attached to those caps.
Here's another
http://www.tnt-audio.com/clinica/ssps1_e.html that I have some problems with... but does touch on some of the things to look for in a filter cap... which heads toward a semi answer of your capacitor types question.
Not releated to your questions though was this gem I ran across while searching, which hits on a pet peeve of mine... coming from the old school days of having anything over 25 watts running your speakers was a big deal... and weighed a ton... so how is that now a tiny box that's light as a feather can put out a kagillion watts??? Here's the answer
http://sound.westhost.com/power.htm. But this is NOT a reflection on the T-Amp... don't know anything about it and never heard it... but it does speak to the snake oil on most of the amps for sale at places like Best Buy, Circuit City, etc.