its fine... it was just that the previous owner had put music or pics on the phone and iTunes wants you to clear it all out so you can put your own stuff on there.... it reads what computer it is connected to ... its best to clear it all out anyway.... welcome to the EI fam... enjoy the iPhone and hang out and share on the boards..
no this only affects the iTunes library it has nothing to do with the firmware.... it should only erase the music, pics, and videos that are on the iPhone... the only time it would affect the unlock is if it was a restore or and update that restored your phone but this is only connected to the media on the phone not the firmware itself
Do you mean pics you have taken with the iPhone? If so, then they will not go anywhere when syncing with iTunes, they will still be on your phone. One thing I would do before syncing is to set iTunes to sync manually and not automatically. That way, you can control exactly what syncs and when. If you have any custom ringtones on your phone, make sure to uncheck the "sync ringtones' tab in iTunes. Also, if you are on firmware 1.0.2 then do not update the iPhone if you are promted to by iTunes, it will wipe all of your apps. There are lots of ways to re-add them, now that the new firmware has been hacked, but it may not be something you want to have to bother with.