Thank you for sharing and these look great!
Regarding butter it is a great substitute ingredient in baking in general and I wouldn't use margarine.
Also, 5 hours is awesome and I'm glad you give it that much time to raise. To help the dough rise I usually put it in a warm place. We have an induction cook top so I turned one of the burners on for a couple of seconds and once turned off I put the mixing bowl with the dough on the warm spot, covered. Or you can heat your oven to super low temp for a few mins and put the dough there (make sure that its off) to help with rising.
Cooking temp wise and timing, we are at altitude so its a bit of a guessing game on how long. I think I cooked them for around 22 mins in total. You should definitely put them right in the middle if you can next time as upper shelf will take longer (as yours did) and may dry them out.