plus, i see trendy fixed gear people with just front brakes and they dont seem to have any problem.
Having only a front brake and a freehub is a super-bad idea. You can't recover from a front skid if you're leaning at all. It works of fixies because you can still stop the back wheel with your legs. In fact, many run without any brake at all. The front is to supplement the back.
The rear wheel needs to be trued. You can do it yourself if you're willing to spend a couple of hours learning how and can put a couple of dollars into spoke wrenches. Then put your back brake back on.
The bike sounds like it needs a tuneup in general, frankly. You might want to start with the
Park Tool site and
Sheldon Brown. When you don't understand something, come on back here and someone will help out.
Be sure to give enough information so folks can help!