Newheli,
For what you want to do, I would stay away from a straight or an A model. The A stands for anemic. I flew one at sea level and it still was short of power. While the C models have the same horsepower as the A's, with the turbo you are getting all of the horsepower. If the blades are starting to delaminate, they are junk and used blades are next to impossible to find. So plan on buying new.
The rotor system is quite heavy and takes a lot of power to add a few RPM, so if you are operating in an area where there are gusty winds, and it sounds like you will be, you will have problems.
As for external loads, I wouldn't consider any model older than a F model.