I don't remember what I installed last, probably some games, definitely not packages from extras-devels or testing.

The last thing I did was to enable Skype and googletalk accounts. There was some wifi connection problem with Skype -- my n900 was unable to log into skype. I read that rebooting the phone will fix it, which i did. But at the time, I never checked my cellular connection.

I do not use any data from cellular connections.

I do not know about cleaned contacts on the sim card. I do know that once my skype and googletalk accounts were setup, some more contacts showed up on my main contact list.

I also deleted my skype/googletalk accounts when trying to fix the phone/sim card problem I have now. That didn't work.