www.mapquest.com is what we use for routing. It will also calculate your fuel costs. We average about $30 per night for RV parks. Some are cheaper and some more but that has been our average for the last 4 years. It does take some doing to keep it below $30. KOA's are nice but more expensive. Food is the same you spend at home if you cook in the RV or grill out. We splurge once a week on a restaurant. We find that our food costs actually went down because we cook smaller portions because of storage space.
In New Orleans, The National World War II Museum is awesome. There are 2 nice parks in that area. French Quarter and Lake Ponchatrain.
We use www.woodalls.com to locate a few campgrounds in the area we stop and use www.rvparkreviews to narrow it to the best bargain.
If you go back thru Mississipppi, we like River View RV Park in Vidalia Louisiana on the Mississippi River, across from Natchez MS.