Hi,
belton!
Tru is a very good club, with three rooms for different types of music: the main room is dance and recent chart music, there's a smaller room for R&B and another for disco-type songs.
http://trubrighton.com/ Take a look at their website so you know what to expect before you go, though, as it's �10 each to get in (and they don't sell wine, either!).
However, there are loads of places to go where you don't have to pay to get in, and don't forget to walk down the steps to the beach; there are loads of bigger clubs down there that stay open until around 6am.
If you're going for two nights you shouldn't have a problem finding anywhere to stay if you Google Brighton Hotels, as pretty much all of them operate a two night stay minimum, but if you are going just for the Saturday night, say, try a day or two before when they might have cancellations. The Five Hotel is nice.
http://www.fivehotel.co.uk/
Failing that (if you get desperate), The Malvern Hotel always has vacancies for around �50-�60 (because it's a bit of a dive)~ it's bearable, though.
http://www.themalvernhotel.com/
Also, for the day after the night before, along North Street is a great pizza restaurant. Eat all the pizza and pasta you can for �3.99.
Have a great time! :o)