Have you read this:
http://reefcentral.com/modules.php?s...showpage&pid=1? It should answer a lot of your basic questions. Then you can ask some more specific questions here.
As for the mated pair of clownfish, that's a pretty good choice. Clownfish are usually pretty good fish for beginners. The only advice I'd give is not to let the fish store sell you two clownfish from separate tanks and tell you it's easy to pair them up on your own. It's not too difficult with some species, but a real challenge with others. If they say they're a mated pair, they should be in the same tank and spending some time in relatively close proximity, not keeping to their own corners.