.. a tool that saves me from doing any math.

Some math, I am afraid, is inevitable...

..mode to specify the length of a wall as distance from surface to surface. Right now it seems the thickness of a wall plays a vital role.

I think we have all struggled with this and it is a recurring topic in the forum. And there are reasons for the centre-to-centre wall dimensions. That said, the math involved is not very difficult once you get used to it. At least if the plan is not too complicated. For instance, in a rectangular room, the inside measurement equals the centre-to-centre measurment minus the wall thickness (half wall thickness on both sides).

Also, do not forget the option of drawing the room first (just inside dimensions), and then double-click with the wall tool to create walls around the room.

BTW, to get measurements right, the AdvancedEditing plugin is very useful.

As for your other comments, some of them have also come up before in the forum.

ok