1) I'm perfectly happy with the data speeds I get on AT&T 3G. I would guess the new 4G phones will suffer in battery life. I don't want to give up battery life for network speed I don't really need. If I had to choose I would choose battery life every time.
2) It's not the cost of the phone, its the cost of the data plan. I would guess it will be like the iPhone 3G launch where AT&T forced you into a 3G plan even if you didn't have 3G coverage in your area.
3) I currently have unlimited data with AT&T which I would like to keep. I doubt very seriously this will be an option with the new "4G" network plans.
4) I can wait for a "4G" phone until there is decent "4G" coverage.