1) I use Missing Sync for Android (see Market for free mobile part; you have to purchase the PC or Mac part from MarkSpace). This application is great, it not only syncs the contacts and diary, but also music, videos, pictures and selected files. Recommended!
2) It seems that the many apps that run in the background kill the battery quickly. I've installed Task Manager (see Market, free) and use Auto-Kill to remove all unwanted tasks. This saves the battery significantly and frees up memory. Recommended!
I've upgraded to the O2 2.1 version from the leaked 2.1 version and no problems so far. I do agree with the bluetooth and keyboard comments.