Welcome!

You don't have to ride fast to enjoy riding a road bike! It's simply more efficient for riding on roads than a mtn bike!

You can stick with plain pedals for a while too (or forever), until you are comfortable with your bike. You can start at slower speeds and work up gradually as you feel comfortable.
Your body will go through a few changes adapting to the new position, so be prepared for a few muscles to object at first.

Try riding a few road bikes around the block or whatever at the bike shop to get a feeling of how they fit you differently. The more of them you test ride the better you will be at sensing which ones fit you well. Don't buy the first bike you see, and don't let salesmen talk you into anything if you are not ready yet.

Have fun window shopping for a little while and building your knowledge base.