Tim -
Questions 1 and 3 are closely related, as higher TL equipment generally has a higher PV. If you're looking to play in a competitive environment, you and your opponents should set some ground rules on allowable TL (TL4 min to TL6 max, for example). With similar limitations in place, 5000 to 7500 points would allow one to field a battalion with support.
For our games, we place black felt squares/rectangles for the urban areas, then put buildings on top for better visual effect. Buildings are removed if they impede model placement, and sometimes we even remember to replace them when able.
