Fascia mounting of the round 18" dish can probably be done. Roof mounting isn't a problem as long as the bolt holes are properly sealed. I've had a dish on the roof for better than 10 years without a drop leaking.
Cost for a pole mount can vary, you need to discuss with the installer. You should dig a trench, but not until you know where the pole will be placed.
Carl
Cost for a pole mount can vary, you need to discuss with the installer. You should dig a trench, but not until you know where the pole will be placed.
Carl