Room (as in space), and as the other person above said. You must be able to control all light. In the studio, you are the boss, so any stray ambient light that is not under you command can be a problem.
Now, the rest.... a good cyclorama is a starting point. You can use a cloth background to start out with. A backdrop stand with a black and white cloth background is a good start. Next will be your lights, 2 at least to start with, studio lights with a modeling light would be preferable, but you can get reflector and shoot through umbrellas to start. One as a main the other as a fill.
A third light for hair lights if you are doing portraiture, or lighting on the cyclorama if you can. If you have not worked in a studio before, there are some books available to help you. I suppose what you need will depend on what you are taking photos of. As I have found that different shoots require different lighting, there is no lighting setup that will do you for everything.
Hope this helps.