First, stop using the right analog stick right now, it doesn't exist.
Second, buffering 360's are easy once you figure out the motion. I usually run the analog stick around once and hit A or B (depending on which throw I want) around the time the stick hits around the 7 position, which registers the 360 and doesn't cause a jump.
720's you can't just do them standing, they have to be buffered into another move, which your going to have to learn to do fluently if you want to get some of the higher damaging gimmicks off. If your doing it on the ground, make sure you buffer the 720 into something that isn't jump cancellable. Use Sledge B (no followup) to start since its one of the easier moves to do it off.
A little side note though, Sledge can be a bit risky in actual matches though since if you put someone into block/hit stun, they can tech out. Applies equally the same to 360A and B too. But use Sledge B to practice buffers though. Once you get the feel for it, practice it with backdashing, other non jump cancelable moves, and Atomic Collider.