well fish wise....you can put in a clown, some gobies, some chromis mainly smaller fish, but there are a good amount to choose from.
for corals, you can do what you like. there are leathers, polyps, zenia, sps if you have excelent lighting. as long as you have the proper lighting for the ones you want.
as for live rock, you can put in as much as you want. but you can also add it slowly. you dont have to buy it all at one time. if you want to have it help as filtration you would add about a pound per gallon.