The domestic cat and the bobcat look completely different, so it would be fairly easy to distinguish them. The bobbed tail cannot be relied on by itself, as there is a domestic breed of cat called the Manx that has a naturally bobbed tail, as well. However, this breed is a bit rare compared to all of the other breeds of domestic cat, which have a naturally ...
Sadly, No. The Pixie Bob is the primary candidate for bobcat/domestic cat interbreeding, but, according to the website of The Tabaxi Cattery, which is a breeder of Pixie-Bobs:
Pixie Bobs are a domestic cat breed with a resemblance to Bobcats,
which originated in the Pacific Northwest region of the United States.
Pixie Bobs are not genetically related ...
Based on your estimation of size, they're definitely cougar. Bobcat tracks should be half (or less) that size.
The Michigan Department of Natural Resources has a nice track comparison page 9with dimensions): Distinguishing Cougar, Coyote, and Bobcat Tracks.
Those tracks are pretty fresh, too. That's a nice find and well photographed.
Bobcats have short stubby tails. The typical house cat has a tail almost the length of its body.
Bobcats have a specific color pattern. House cats have all kinds of colors and patterns due to the human selection and lack of natural selection.