These are good suggestions.
Using more pixels for white balance sampling is something I was already planning to change.
"-Some way to reset rotation back to exactly 0 degrees ( Or is there a way to do it already? )"
-Yes, sort of. If you click on the 90 degrees rotation buttons, it will rotate to the nearest 90 degree multiple.
"Use a folder in the users directory for "Picture Data" not the installation folder, because when run without administrative privileges the "Program files" folder is not writeable, causing the previews not being saved and giving an ugly error on exit."
-That's a good point. I didn't run into the problem, as I'm always administrator on my machine.
The slider precision issue has also occurred to me, but I wasn't aware of the mouse wheel method in Lightroom. Sounds good, I'll implement it.
Thanks for the feedback!