RE: plane rolls with elevator
Lateral balance is a good thing to check as has been mentioned.
Another thing that is often overlooked is how your two ailerons are versus each other. A somewhat finer detail of that is how are the ailerons in relationship to the wing.
I flew a guy's airplane for him today. Before doing it, I did all the usual checks. Pushed all the sticks and watched which way and how much the surfaces move. Did a balance check. Everything I did checked out. Flew the plane and it flew ok but took quite a bit of aileron trim. And something didn't seem right. Couldn't figure out what it was while flying. But planned to look at the aileron trim on landing and talk him into adjusting the trim into the airplane (he's a believer that computer radios were put on this earth to solve any connector problem).
On the ground I noticed that both ailerons had the "down flaps syndrome". Turns out that a couple of high speed stalls that I had thought were just the blustery wind could be explained by the ailerons. All the trim plus the down flaps had made one of the wings have a bunch of "wash in" so to speak.
When you ask an airplane that has some aileron trim to pitch, sometimes the down trimmed aileron wing will stall before the other. And sometimes the up trimmed aileron wing just won't give near as much lift as the other wing. Depends on the airplane and what you're asking it to do which symptom you see.
And what actually could be the cause when you've got an airplane that took a significant aileron trim setting....... whatever twist there is in the wings that caused you to have to counter that with trim. BTW, every airplane you've got with significant aileron trim on it.... check for warps and get 'em out if they're there.
It's always worth the look to stand directly behind any airplane and make sure the wing and ailerons are true.