If you can find room for a set of your wheels, take them along when you visit the LBS. Then you are only buying the cone wrenches you need. The front cones are a different size from the rear cones. You might only need new bearings which are inexpensive.

If you have access to any waterproof grease, that will work fine. The stuff used on boat trailers is perfect for any area on a bike needing grease, including the jockey wheels on the RD.