it is important to have your top pressed nicely and it be squared. if there are many seams along the outer edges it is also a good idea to run a straight stitch all the way around the outter edge. this keeps the edges from being pulled apart when the quilt is loaded on the frame...it is pulled taut.
you will need to contact a local quilt shop to find out who in your area provides the services you require; prices vary depending on lots of things including location...it's going to be different in Michigan than in Florida. and some will square the quilt and bind it for you after quilting, some will only do the quilting...i don't know (any) who provide the backing, usually people take their top and backing to the quilter...backings are usually individual ...for that quilt...and should be (at least) 5" all the way around larger than the top...which means if your top measures 80"x90" your backing should measure 90"x100"---the batting has to be larger too, but some long-arm quilters do offer some batting. after contacting a couple quilters in your area you need to visit them - see their work and discuss pricing; some charge by the quilt, some by the square inch, some by the hour, some charge for thread, some include thread...some people do only free-hand custom work, some use panto's or stencils...some have computerized stitchers....you want someone who does the quilting you like...it is important to establish a relationship with your quilter. as for what you can expect...cost wise...no way to tell since you did not say what size the quilt top is...anywhere from $40-$50 for a little baby quilt up to $400-$500 for custom work on a King...it all depends on alot of variables. and any willing to square and bind after quilting is going to charge extra for that.
if you do a search here there is a list of long-armers on the board, you could check the list to see if there is anyone close to you and ask specific questions too.