Moving air through a pipe doesn't really car if if it (the Pipe) is going up, down or sideways. Sure up is always better because you gain the natural rising of heated air, but plenty of setups flow down. Where do you think the air in ALL downdraft hoods and JennAir's flows??? Re: remote vs. internal- either type will work AS LONG AS the selected unit pushes/pulls enough air (cfm's) to overcome the static pressure of your pipe and all the bends. Remote or inline ones are generally quieter than hood mounted ones.

If we go with a 25 or 26" deep fridge cabinet, the fridge unit will be pulled forward also so it is flush with the stiles of the cabinet. The Thermador Freedom columns are designed to sit flush in a 24" deep cabinet (I assume that includes the plug and water line, but will have to verify.) I believe the door panel will add 3/4" to 1" of depth, so total depth to the front of the door would be about 25", but I expect the same will be true of the cabinets once the doors are added to the front. I saw an in-store installation that I loved, which had the SS column flush in a wall with 3" wide wood trim/filler on each side framing the SS. All the cabinets and appliances on the display wall were tall and flush, so they did not address the counter issue. I had pictured the doors of the columns being flush with the flat panel drawers of the lower cabinets in one straight line. Maybe I could go with a narrower counter overhang so the counter ends flush with the front of the drawers instead of hanging over, or is that a terrible idea?

It appears to be a carpenter's mistake since the intention of the design is clearly stated on the drawings. Perhaps the windows were installed before the door arrived. IMHO there is no reason to replace anything other than the narrow "picture frame" molding; it's really out of place here. Option A (cheapest) Raise the door head trim and find a way to fill the resulting gap. I would also fill the gap between the door and window jamb trims because these narrow strips of wall look amateurish to me. Option B (best) Use 3/8" or 1/2" flat trim that spans from opening to opening, then add a decorative band molding around the outer perimeter of the entire assembly. The flat part of the trim would be a bit larger at the door head but it would look fine since it's at a door not a window. If the carpenter is good he could add a cove, bevel or bead at the inner edges. That is the way triple openings have been detailed for hundreds of years so I'm surprised the architects or the builder didn't suggest it.

Our fab. cut our L shap out that fit on one slab, then cut the seam from that and they also fit the 3 inch backsplash on there prior to cutting from what they said so everything blends nicely for the one side of our kitchen. There was no way to lift the granite (in less they had tons of people and even then moving it around our tiny kitchen was very difficult as it was) without the seam. Ours put a lot of thought into it, which was nice and we didn't have to micromanage, which was even better. They had to use two slabs, but the other slab was used on the other side, so it was a non-issue of it matching up perfectly.