This is partly why even till this year, I normally measure on site and draw 2D in PowerCADD, and then turn it into 3D in SketchUp back at the office. I tried an experiment last fall drawing on site with SU for iPad, but it doesn’t do Dynamic Components (or Match Photo for that matter).
FlexTools comes with a bunch parametric doors and windows, and you can resize them with the scale tool without distorting the inner parts. Out of the box, they’re all metric, but you can switch to imperial and change them.