First, for a twisting backflip, whether it's 180, 360, 540, or anything, you can basically use the same technique. Keep your body flat, jump up, and throw your arms UP, and to the side that you rotate. Bring them in to spin quickly. Of course, with this, and most Freerunning moves, no one can tell you exactly how to do it; you have to learn for yourself.
Try it in a safe environment, and slowly get a feel for what you have to do. 90% of Freeruning is knowing what you have to do in a move, the other 10% is skill. Try it on a trampoline first, and slowly decrease your amount of bounce before it until you can do it standing. Then try it on a soft surface with a roundoff or roundoff-back handspring. (If you can't do these, consult a gymnast.)
Now, the second thing you described is called a gainer. Again, don't just try this anywhere until you know how to do it correctly. To see if you're ready, find out if you can do a backtuck, landing in exactly the same spot you took off. If you go backwards, you're not ready.
There are variants of the gainer, but the most basic two are the two-foot and running. With a two foot (it should be tried off of a short drop at first) stand and do a regular back tuck, pushing your hips forward and thinking forward. But jump up. That's really important. If you jump forward, your momentum will prevent any more than a half of a backward rotation. Jump UP, think FORWARD, TUCK.
With a running gainer, approach at a moderate pace at first, jump high, and kick one leg back like in a flashkick. But the kick only initiates the rotation, especially on a small drop, and you'll require a tuck to nail it. So RUN, JUMP, KICK, and TUCK.
Good luck, and be safe!
