There's a great book by Linda Taylor "Ultimate Guide to Longarm Machine Quilting"
http://www.amazon.com/Ultimate-Guide...chine+quilting
It's geared toward long arm quilters and has several examples of agreements.
If you are dropping a top off at a long arm quilter and she doesn't have a formal contract, I would still insist on something in writing, stating the size of the top, color thread, type of batting (and who provided it), type of quilting requested and/or name of panto, price and a target completion date. Just write this all down on a sheet of paper and both of you sign and date it. If she doesn't have a copy machine, write it up twice so you both have a copy. Also, don't just drop the quilt off and run. Plan on spending a bit of time with the long armer to look at your top, especially if you are a new customer. Ask to see samples of her work. As far as providing the batting, I would contact the quilter. Often they buy in bulk and can offer a price that is competitive to what you would pay.
Most established quilters have a brochure or prep sheet telling you how to prepare your top & backing.
If the quilter doesn't want to provide something in writing (formal or not) and/or doesn't want to take the time with you up front to look at and discuss your top, I would look for a different quilter.