Good story!
Your antenna will get it's job done the best when it has a clear view of the horizon in the direction of the towers. Trees, buildings, etc are not reception friendly. Sometimes, towers can be all around you, which can make the situation more challenging; antennas are directional. Roof is usually the best for signal strength. The attic may work. I always say if you want, run a length of cable and try it out with a quick attic test. If you get everything, you're good. If not, you move it outdoors. No harm done.
You can probably reuse the sat coax. Just be sure you remove anything sat related from it. It has to be used by the antenna exclusively.