If possible, I would have the new dish installed on something other than the roof
Roofing companies love satellite installers, as they do nice jobs creating leaks
In the spring, I would go up and have a closer look at it, just to make sure it is sealed properly, and not loose
Installers rarely hit a stud/joist in the roof, so the dish is being held by a piece of plywood 5/8' thick, or around there
Just something to scare you, jk, I would check it out
My fingers are crossed you have a sealed roof
You can use the mounting arm (mast) but you'll need a Star Choice specific dish.
Make sure you still have a good line of sight. ExpressVu and Star Choice satellites are about 25 degrees apart in the sky. Based on your location, the SC satellites will be up and to the right from the EVu ones (when looking from behind the dish).