I have all the specs from a quadcopter, everthing, would it be possible to figure out the pid from those specs?
Generally, no. You'd have to evaluate the system and do some system identification. The reason being that even though you know the specs, you don't know how the system will respond to perturbations or errors in manufacturing, etc.
Once you've done some system identification to figure out response curves, you can tune the parameters using the guide in the comment (or here).
Another method is to just fly it around a set point and observe its behavior, though I think that's not the best solution.
Quadrotor Control Problem
It depends! You have a good mathematical model? After you achieve one, you might need to choose a good system identification method. Comparing their outputs you should have enough data to start thinking on the controller design.
Beyond this, I can't say precisely what you want or need...