Actually version 4 saves the last page, I used it quite a bit, but it appears that under 2.7.1 it isn't.
Centering isn't a "bug" its a personal preference. I didn't like the pages centered because with some PDF's the odd/even pages would have different widths/heights and would dance sideways or up/down on the screen as you flipped between the pages. So I pinned them into the upper left.
I also didn't like the black border iRex drew around the pages.
The centering seems popular so I'm putting it back.