Best way to seal/insulate a replacement window in New Englan

[bluenote]

So I've been doing quite a fair bit of research prior to taking on a replacment window project. I currently have old wooden sashes with storm windows which I plan on replacing with vinyl windows.
I'm going to insulate the sash weight cavity. However, what is the best way to completly seal the window?
Prior to caulking the exterior stop and placing the new window, shoudl I lay out some sort of self sealing membrane? Is this overkill? Should I repaint and reseal the exterior stops prior to install?

[Windows on Washington]

Low expansion foam for window and doors.

[bluenote]

So shoudl I flash around the entire window or only at the base?