For the horizontal and vertical swipe I didn't know this was normal. I used mostly the vertical swipe an if you take your time scrolling it works.
I don't know how I did it, but I managed to deactivate the bouncing/swiping while using it. Does that mean you can give us the choice to disable it? I don't mind it but know others do.
I have to say the thing that I was the most afraid of was the latency and battery draining, but setting the scaling quality to low made it just like 2.2, smooth as butter. I just didn't think my mac was that old :P
When I talked about the option to mask the mouse and the scroll bar, I just meant to hide (the mouse especially).
Now the only "big" problem I have is : "When changing images it stays at the same "zoom position" which was an option you could disable before." I hope this comes back in 3.0 along with the always open in fullscreen option.
Other than that great job, the application is already very stable. Keep up the great work ;)