Oh congratulations. It's like a love affair when you first get it--can't stay away. miss it when you're gone for one day, worry about it. I quilted 50 quilts for Project Linus in the first 2 months I had my longarm.
Regarding tension-- oh yes, they take a lot of fiddling and futzing. Try doing some practice with Isacord cotton thread in both top and bobbin. I find it a very beautiful thread that quilts easily.
Have fun. Breathe. Remember you are pretty new to this and just enjoy the learning. Practice. There are great books and DVDs. I don't know whether you have used a longarm at a shop or if you are really a novice, but if you're interested in learning tools, let me know and I'll send you a list.