As said, I won't give any time-frames, so don't put all your hopes just in me.

Your editing suggestions look good, and I think they provide a nice template to follow. So with a detailed editing instruction like that it shouldn't take too long to change a scene. Editing is the easier part of any changes... digital changes take a lot more time to do, and I think the editing itself can be learned quite quickly... the web is full of tutorials regarding that (and I think there are some links in this thread as well).