When I started to road bike again, after doing the MTB thing for a few years ago (and doing fairly well in crits in college some years prior to that), it was MTB shorts and a T shirt.
Very quickly, I learned that both good cycling shorts and a good cycling jersey make a lot of difference. You're not drenched in sweat, and there's nothing rubbing or flapping in the breeze.
Clipless pedals - they're weird at first, then you get used to them, then you wonder how you did without them. Getting out becomes instinctive, and then it's not an issue - pop one foot loose as you're slowing down just to be sure. And they're a lot quicker to get into than the old clipped pedals - how many times I did the toe flip thing trying to get the pedal in position...