Hello Tim, and welcome to FOTMD and the wonderful world of the Mountain Dulcimer. The first thing I would advise is to read the following:
http://mountaindulcimer.ning.com/profiles/blogs/i-just-got-a-dulcimer-now-what
Ken is a member here and a highly respected one.
You're current tuning is the most popular and the string set will be just fine for that. We normally call that tuning DAdd listing the bass string first then the middle string and the melody strings last. Since most play the mountain dulcimer on their laps, the melody strings are the ones nearest you, then the middle with the bass the farthest away from your body (assuming that you are right handed). Ken's blog should get you started then you can ask all the questions that you have. There is no such thing as a stupid or ignorant question here at FOTMD. Have fun and happy strumming.