Using other then o2 sim card in iphone

No, I dont think you will be able to surf the net, unless you get a package for whoevers sim you put in, or alternatively via a wireless connection.

If you jailbreak on V2 firmware but v3 has only just come out so jailbreak for this will take a week or so but people with jailbreak on V2 havnt complained so much about using all features so no reason why not.

I know someone that had an i-phone running vodafone, obviously he had to get the phone chipped which can cause other problems...he had no problem surfing the net and using the google maps, what was an issue was when you get an update through iTunes, this can cause a fault to be found with the phone making it useless...it would mean another visit to a shop to hack the phone again, not sure whether you'd beable to upgrade the phone at all, I've just upgraded mine to 3.0 which now allows me to send mms and a couple of other features...the person who had this i-phone in question doesn't have it anymore as the screen when blank and the money to repair it didn't justify the outlay, don't know if it's anything to do with the phone being hacked or just bad luck...