I advise you use the firmware you find on Apple's servers

Just let iTunes check for updates and when prompted select "Just download", iTunes will download the iPhone software and place it under ~/Library/iTunes/iPhone Software Updates/, PwnageTool 2 should be able to find it automatically.
Restoring wipes everything, bot data and settings so as long as it's on iTunes, Adress Book and iCal it will come back just by syncing.
What won't come back are notes and system settings, you should eMail yourself your notes (you can extract them from the backup but it's not a easy task) if you care about them.
I'm noticing few issues with the final 2.0 myself but it's nothing unbearable, the only thing that really annoys me it's a few bugs with the iPod that I'm not even sure depend on the iPhone software.
Bookmarks