I can't really comment on what constitutes a structure. I've typically started a small area to build/grow from and request via PE for the base protection. It can always be extended later. For turf griefs you would want to file a separate PE to report the damage. A structure, even without region protection, is a protected work in minetown law.

It feels like a chicken and egg scenario, but that doesn't really seem to be the case. I suspect there are a lot of bogus region protection requests with the fulfillment on the builders part not being completed. Thus in order to cut down on bogus protection requests the mods typically ask the area be developed.

I'm about to start a large project as well and I do plan to put up signs warning potential thieves. When I'm happy with the outter walls I'll file.

I don't know if land clearance costs come with an associated protection. It merely sounds like a land clearance package so I'm not sure how that applies to the issue. Regardless, donation does not exactly equal entitlement and they have always stressed that. Me, I don't mind the perks I get from donating, but the purpose wasn't to buy rank in minetown. I donate (like many others) because I want to ensure the place continues to function.

In any event, sounds like the major issue you are having is griefers. Report em!