I've been feeling swervy in the past couple weeks, and finally looked at my rear tire--realized the middle 2 inches or so has no tread left.

I have 2 questions for you folks:
1. The front tire (a Conti zippy) seems fine, but should I replace it at the same time?
2. What rear tire are the cool kids buying nowadays? N.B. I hate whitewalls.
I greatly appreciate your advice, as I gingerly ride around town, eager to order a new tire or two.
Thanks,
redcass