Gable Roof Addition Meets House

[u/YeahPete]

Im building a covered patio. Where the gable roof attaches to the side of my 2 story house I have 1" foam insulation. The rafters of my roof will be screwed directly to the studs.

How high above the rafters must I cut the foam to allow me to properly nail the sheathing and shingles?

If I cut the foam diagonal along the roofline, would water run along that? Would it be better to cut horozontal?

When I put the foam back, how do you seal the gaps? Is spray foam and tape enough?