It takes XX amount of power to move YY pounds against ZZ wind resistance.
To produce that XX amount of power requires KK amount of fuel. There isn't much you can do to change that. The advantage of the Ecoboost is that it doesn't produce that power when it isn't needed thus saving fuel when not towing.
Fuel usage when towing will not be much different than any other gas engine because it still requires KK amount of fuel to produce XX amount of power.
Regarding sway, go to the towing section and read the stickies about how weight distribution works and how to correctly set up your hitch before throwing money at it.