Each person will have different requirements. Most longarmers do not want you to baste the quilt. Depending on who you have do it they carry things like backing material and batting that you can purchase from them, but you don't have to. You can always buy your own and sent it with the quilt top. Depending on the longarmer they like between 4" to 7" all the way around extra for the batting and the backing.
When you have something hand quilted every little bit that you do saves you money. If you baste the quilt that will save time for the hand quilter, if you collect all the pieces that also saves them. Normally with hand quilting they charge by the "yard of thread used" so each quilt gets a different price at the end depending on how much quilting. But the quotes I've seen from places online it's about 4x as much. That is not always the case if you can locate a hand quilter yourself it will not cost nearly so much in overhead.
As someone before me recommended my local quilt shop will happily put you in touch with a longarmer or a hand quilter that they know through the local quilt guild. Spend a little time online and sift through to gain information.
For instance a computerized longarmer is a bit cheaper because they tell the machine to sew and off it goes on any number of preprogramed patterns. Vs. a handguided machine costs a little bit more because you are paying someone to sit with the machine and guide it through there are all different ability and skill levels for this last. The more years of experience the more they can charge. If you type "longarm quilting" into a google search you can get an idea of the different price points and what their requirements so that when you do meet with someone you will be on a more level footing with them.
Once you've looked around a bit on line you can expand your search to be "longarm quilting in new york" ect. and you can use that to help you find a quilter as well.