I'm looking for my first lens that I can use with my 5x7/4x5 camera for portraits hence my interest in speed.

Portraits is the main purpose, but can this lens also be used as a general all purpose lens?

I'm a bit lost with all the choices. I'm also looking at the Commercial Ektars, slower & sharper I bet, but I can always soften up with a softar etc or in post as a last resort? I'm not sure I can get the selective focus I want with the 8 1/2 inch/6.3 lens though?

Will these type of lenses fit/work (size/weight) on a 4 inch lensboard?