With regards to the render size, goto Render->Render dimensions and in the dialog box select Fit in preview window, then click the Match Document Window button. That should give you the correct render area.

I've also just had a thought. As you have been using the dolly camera view to position the main camera, have you reselected the main camera view to render from? As you show, there shouldn't be anything in the main camera view, but from where the dolly camera is looks prime for being in a wall.