Don't worry about phone number showing as Unknown. Almost all Korean phones show this behavior. But it should show you "UFone" in the Notification Area, when you drop down the Notification Menu from the top.
However, if the SIM is not working then it can either be: 1) SIM is old and should be replaced with a new one. 2) Baseband of the phone is corrupt (in which case NONE of the SIMs will work on it).
Im sorry yar, i forgot about your VM.
Coming to bios updates, when i updated my laptop's bios i lost a lil battery life and gained nothing.
On the motherboards side, it rectified some problems like the computer wont wake from sleep, auto ocing etc.
So if it is an update u may do it, i dont think there will be any harm in doing so.