If you practice standing with a strap, you want it adjusted so that your forearm and wrist are in the same position as when you're sitting. You will probably have to experiment, and readjust it a couple of times before you feel comfortable with it. Most everyone has a different preference, but you don't want the guitar to hang too low. This can cause other problems in the future, and it seems like you've got a handle on the earlier problems now.

Have a great wekend, and enjoy playing that new guitar.