That's not something you can cover in a forum--any forum. You'll get nothing but scattershot anecdotes. It's a waste of everyone's time. All of that has been written--in great detail by professionals--in well-structured, focused, reference articles. Do some googling.

This forum is about design problems and questions, not home building, construction, or finance.

If you want to waste time, at least ask on a finance forum or a construction forum.

Get an architect .

@Patricia thanks for the feedback, could I just buy a design instead?