Maybe overkill and **** but I would put in some bracing/jack studs before knocking anything out. Hard to tell from the picture if the porch roof and deck load is being transferred onto the front wall.Not ****.....maybe a bit overkill......but hard to even say that about good solid construction.
Given there does seem to be some pressure from above that may have cracked the window, you might want to get at least a vertical stud beside the wall and as much of a wood header above the proposed door as you can get for some reassurance, but yeah, other than that cut out below and whatever you have to do to get it in.