2. Only the 1st and the 5th are patio doors =>
depending on how much heating I need, I may only need
heaters at the 3 windows

Now, in terms of heaters in front of windows I have a couple of options:
a Small radiators sticking up from the floor in front of the tall windows













b Bench-like radiators in front of the tall window













c Windows that go only to 18-20" from floor and build out of bench-like structure.















So, how about some decision making ;-)