There is no such thing as a PB632. You mean PB623 (I assume)
Yes, you can reassign keys.
Also, the default settings for the touch zones are designed so that you can use it with either hand. (Tap mid left or mid right to page forward, tap bottom left or bottom right to go one page back).
There is a version of Coolreader that you can install yourself on the PB readers that in addition allows you to reassign (and even resize) touch zones.
New PocketBook models still read folder structures.
Note that there is a successor to the PB623 out now, the PB626 or Touch Lux 2. Improved hardware features but audio support has gone.