Surfing Waves

I went surfing for the first time on vacation about 2 weeks ago. I really liked it, and want to go back out in the water. Only problem is that I don't live near the ocean as I live in the Midwest (in the U.S.). I live on a lake, where I can do surfing conditioning such as swimming. I was thinking of getting a board so I can just paddle around my lake.

What kind of board should I get?

Also, is it bad for beginners to start out on shortboards?

Forget the short board idea with your situation and limited real surf time. Each time between ocean outings you will go backwards inability to catch waves. Less waves = less progress ,

Paddling around your lake is a good idea on the board you eventually choose, but that will in no other way than just paddle strength help you on judging how to paddle for waves ( position timing match speed etc).
Read through the threads in this section and match what is being said about age weight, height and how that helps in choosing your board!

Check this out....if you are near the Great Lakes you might be closer to surf than you thought.....