Don, here's a follow up to some of those items you wondered about.
First about the two sized oil can...
I was sure at first it was an oiler like this placed in a larger bottom can.
But upon closer inspection it is indeed one can.
It was obviously two cans that the manufacture combined to keep the tooling costs down and then were able to offer a can with more volume. When you unscrew the top, it has a long pickup tube the goes the length of the can. I wanted to take a picture, but it had oil in it and it would have been very messy to do so.
Next the heating tanks. They were never used for anything special that my friend can remember. He said his Dad was offered them and he kept them "in case" a need for them ever came up. It never did. My buddy did make a hog roaster out of one of them. He said they were the perfect size for that.
Now about that weight...
...the one with the cast in handle. Here it is after I had it powder coated.
It has US STANDARD cast into it. I could find no other marking on it. I believe it's a 50# weight. I don't know what it's original use might have been. There were no other scales on the property except for the one pictured earlier.
Lastly the stone bush hammer...
That makes much more sense. What Mr. Johnson used it for...who knows?

Note from this view that the handle is off set. There were no markings on it. Once it's cleaned up. perhaps something will show up.
Now Don, don't get sun burned in sunny Devon, OK? Thanks for your interest.
Thomas