I'll let some of the other (more seasoned) riders chime in on what bike you should be using. I started commuting recently and have two bikes. One for good weather, one for not. Both are comfortable, which was the biggest thing for me.

Congratulations on the gas savings and making the decision to ride. My commute is about 10 miles less than yours. It'll take some getting used to, but just do it and keep doing it. You'll love it.