well to try to help out, all clownfish are born males, and when in a group the largest male becomes a female and will pair up with one of the other males. at that point it's not good to have a 3rd wheel really, as the 3rd male will likely be the target of some aggression (depending on the species).
No clownfish needs an anemone, and frankly keeping an anemone alive can be quite difficult. There are a number of corals that a clownfish may accept in the place of an anemone, and they will also find plenty of other things in the tank to host with (but it does not look at neat).
Captive breed clowns most certainly will host with an anemone. There may perhaps be the special cases where they won't accept certain types or one at all, but you can't breed out a natural instinct that has been ingrained in their genetic code for years over one generation. I had a tank breed maroon that took to an Atlantic Condy anemone just fine, and they aren't even supposed to host with that species of anemone. but the anemone died over the course of 6 months...
As for as tank setup, there are a number of good books and thousands of threads on this forum (hundreds or more dedicated to the topic of tank setups), so I won't go into that too much.
I will say do some research before you buy. It will save you time, money, and headaches.
Guy