My new-to-me house is solid masonry, the walls are 2 courses of bricks over cinder block. The garage had been converted to a family room at some point. The garage doors were converted to large windows with bench seats on the inside and the non-window part of the openings are sided in stucco--no idea if it's over masonry or framing, but I'm guessing framing.

There is still an unneeded exterior door that I would like to replace with a window and a wall with a similar stucco finish to the two windows adjacent to it. I'm pretty handy and am confident that I can frame out the wall and window, however I'm not sure how to "attach" it to the brick opening. I know that masonry anchors can secure the framing to the brick but I am concerned about water intrusion. Would simply filling gaps with foam + caulk be sufficient? Should I leave a gap between the stucco and the brick itself, or would it be ok to stucco all the way to the brick?

The bottom of the door is very close to grade (part of the reason I want to get rid of it), so I'm even more concerned about water intrusion there. I am thinking about doing similar flashing to what I would use if I were simply replacing the door with another pre-hung door--and use all pressure treated lumber, however I'm just not sure if that's going to be sufficient.

As an alternative I suppose that I could use blocks to build up the wall, but there my experience level drops off so I'd rather frame.

Any tips or advice would be greatly appreciated!