I don't remeber seeing anything from befor ethe late 1930s with a Madison sticker. Neat.
The stamp might mean it was sold by Madison, rather than being fixed by them.
Regarding photos.
In Windows 10 photo viewer, with the photo open select the settibgs . . . then select RESIZE (3rd down). In resize you can save as option C define custom Demensions. Select 1200 for width which should set height to 900 automatically, Check MAINTAIN Aspect Ration, and with the quality slider select a value between 40-80%.
The sweet spot is about 80-120KB for a 1200 by 900 image from my camera is at 75% quality . It will take some experimenting, but once you find it, it's the same every time.
With the Windows Photo Viewer, you can import from the camera, and then open and save each picture to a new location. Those pictures are then uploaded.
I just took a picture of the dog as an example.
40% is a size of 70KB
60 percent is 99KB
80 percent is 129 KB
You can use the arrow in the viewer to move between those pictures. Not much of a difference I can see.