What you want can probably be done and the majority of it is in the Edit menus for the aircraft. Most of the standard stuff is easy to figure out but much of it is a bit unclear to many of us accept InertiaSoft since there currently isn't a manual that documents any of it.

I'd begin by selecting the closet representation of your plane and rescaling to your chosen dimensions. From the main menu in FSone, click on Aircraft, select a model that is a close representation of yours, click Copy and give it a descriptive name. Select the newly copied aircraft and choose edit then choose Scaling (size/wt). Much here should be self explanatory. What isn't obvious non of us know because we don't have a manual. Once your done scaling the list on the left should point you in the right direction. Mass will allow you to fine tune the weight and CG, Propulsion will allow you to select a motor and prop, Sounds are just what you want the engine to sound like, Servos allow you to change endpoint, angle, travel etc..... If anything this should get you going.

$.02

Ken-