There are lots of conceptual problems with exporting XML for "backup" purposes, even when using the system view format. Exporting and importing this way will lose information, including version history. It's simply the limitation of the standard JCR import/export semantics. We created the backup and restore feature because it would be a much better (and faster) fit.
I think you're running into the second problem because of timezone representations in the restore process. Can you share the backup that has this problem, or if not recreate one that does? Firstly, we need to fix the problem, and I can't figure out why the date format is wrong. Secondly, we need to improve the trace logging of the restore so that, via logging, one can determine what is going on and where it failed.