You can see pics of my install at
http://www.klenger.net/arctic-fox/stereo/index.html
When selecting a location for the antenna, it is not necessary to have a totallly level spot, but the more level, the better. Only problem with an unlevel installation is that the elevation will change as the antenna is rotated, but this is easily fixed by adjusting elevation using the digiital magic meter. You can also buy a beveled shim to help compensate for roof angle.
When selecting a location, be sure to consider obstructions like roof racks, sky lights, etc. on the roof as it rotates. When elevated, the antenna rises quite a bit, so most obstructions are not a problem, but keep them in mind to make sure the antenna doesn't hit. I spent a lot of time measuring and remeasuring before drilling any holes. Once started, the install went pretty well.
As far as I know, the antenna you are getting is a single LNB, which means that it can only be connected to a single SAT receiver. If you want to run two TV's from it, they will both need to be connected to a single SAT receiver. One could be a direct connect using RCA or S-Video and the other most likely connected to the RF output of the receiver.
If you have any more questions, you can email me at -- email address removed --. Good luck and enjoy.