I would check with the shop and see if their machine "likes" water soluable thread. That should answer a lot of your questions right off. If it can't, I would see if she offers a basting service on the longarm. She might baste the sandwich for you at a nominal fee and it will be ready for you to machine quilt. If you just want to try your hand at LA quilting, bring in a cheater top (printed design) and quilt your heart out. It will make a great picnic or car quilt and it might turn out nice enough for a extra winter blanket.