Hi Peggy,
It can vary widely based on what kind of window you have now (aluminum, wood, vinyl, etcl) as well as if you have brickmould casing on the exterior etc. It can be up to 5" different. Just ... read more
The difficulty depends on many things.
I would say PT post is the way to go, but install it over a post standoff past so water doesnt get trapped between the bottom of the post and whatever it is sitt ... read more