brassvols, you are 100% on that being a dog trot , but i doubt they lived in it , you can tell if you look close at the picture the door opening is wrong , it is not a cased opening , the door was hung on the outside face of the logs , which was common for barns , a couple other things that make me say it was always a barn is the lack of windows and no daubing/chinking not even boards over the cracks .. after looking over the pictures again i think picture #5 looks like the log residence . but its hard to tell from that shot.
and again you are right about the cabin was usually the original homestead , in most cases they would build on as the family grew and eventually cover the log house in clap board siding to add protection from the elements and hide the logs, after all a log house back then was a poor mans house , if you had any money you bought saw milled lumber .
sorry i get carried away , as i said earlier i restored antique log cabins and love talking about them,,lol
if that structure in picture # 5 is a house i would bet it was the homestead.