pitbull .... to heat up your house, you can close the damper. It will help it heat up a little faster. The important thing is to open it when you put the jerky in, initially. You want it to dry off a bit, and become slightly tacky. This is a tough thing to describe, and harder to figure out if you are not familiar with smoking meat.
When you deem your jerky dry enough, then you would close the damper, and put the smoke to it. With the damper closed, you won't waste your smoke, and it will stay in the house, and "flavor" the meat. Once the smoke has dissipated, then you can open the damper, again, and turn up your heat. Now you will be doing the finish cook on the jerky, and drying it out.
The over dry edges makes me think the slices might be tapered a bit. It's tough slicing meat, that the ends aren't square. You will almost always have this issue though. It's just something that we have to deal with. I have had too much heat, in the bottom of my house, and usually have to rotate my racks around a little bit, and take out the done pieces as they finish.
Hope this helps.