2.No (The 2G uses a different package and upgrading will flag you to the 3G smartphone package; which you were not a part of before so it doesn't carry over. Unless you don't tell them and your account stays as 2G plan but then you are limited to edge service but they may do scans and auto add the iphone plan to your account.)
someone found a workaround for this. not sure if it still works, but it would be worth a shot.
he said you buy an iPhone 4, remove the sim and install it into the original 2G iPhone. you will have to tape it in place so it doesnt move. Then activate the unlimited data on the iPhone 2G while your iPhone 4 sim is inserted. When complete you receive a message saying your data plan has been activated.
Then you remove the sim and put it back in the iPhone 4, and at&t will send you a message that says your data plan is now $30 per month due to having 3G connectivity. and voila, unlimited data on a new iPhone.
Again, at&t may have caught this loop hole by now, but i would certainly try it.