Same here, even though I get 0 to 1 bar at my place of work, but good bars everywhere else, they have wifi which still allows me to text to the wife if need be.
I have a feeling the Verizon iPhone will be a little more expensive in plans. $5 more, but you get more data instead of the measly amounts AT&T offers.
No, you can text your wife because 1 bar is usually good enough to send a text, hell, zero bars and you might be able to do it if you barely have a signal. It has nothing to do with WiFi. Text messages are not sent over the WiFi network. Never. Unless you're using some 3rd party service.