Michelle - Good for you for thinking about this now :) Longarmers are very much accustomed to walking new clients through their specific requirements. It does seem to vary with regions, as to what those requirements are, the charges, and the batting preferences.
You do have a choice to use a local LAer or you can use one by mail. It is usually best to use one in your area so that if there are any issues, they can be dealt with properly and quickly. Plus, you will be able to see many examples of their work up close. It may be nice to begin asking around for references for your local folks now, and then you can also begin to hear if they are good, how people like working with them, their backlogs (which are very common), etc. Reputations,in this business, are everything.
Most LAers are wonderful to work with, and will appreciate a nicely pressed and squared top and backing. Usually you're allowed to use whatever batting you prefer, but it's best if you ask about the preference as there are some that are a bear to work with! Also, you will have your choice of threads, type and color, as well as the patterns you prefer - whether hand-worked or computerized (both are lovely and both can be awful - so no guarantees on one over the other!).
Please feel free to ask any additional questions. I'm happy to help if I can.
Hope this helps :)
Debbie in Austin