The mounting and squatting behaviors, like any sexual behavior, is not magically restricted to either gender and does not prove nor disprove gender just by presence or absence of that behavior.
It's likely in one gender and unlikely in the other, but by itself does not prove anything.
For an example, I had a proven hen mount and mate with many roosters, and they squatted, complained, and spread their tail feathers as a hen does. They were proven males and she a proven female who later went on to be a prolific layer and mother. I have also had other proven laying hens mate with hens. Not just mount, they mated.
For another example, baby turkeys take turns playing boys-n-girls, with one displaying and gobbling as best as its baby lungs can, while the other lies down. It's complete with mating behavior, but all non-gender specific in terms of who does what. As soon as one is done being the girl it will be the boy and the other will then be the girl, swapping every time they mate. Some male chickens mate with other males. As always, gender is a guideline, not a hard and fast rule.
Babies too can mate 'successfully' in terms of the physical mechanics of it, but of course are infertile for a while longer. Some chickens are extremely precocious. I've had one a few weeks old mating with adult hens. It was less than a quarter of their sizes, and they were bantams.
Quote: The bunny tail is a genetic trait that isn't actually tied to gender. No real guarantee there. Some bantam males, an even large fowl, can have very curled or undersized tails that look like a hen's except slightly more tapered. They're not 'wobbles' --- though I think that's a funny and good term for them --- they're 'wattles'. A lot of people call them 'waddles' like what a duck or goose does. If its crest and wattles are more developed than all the others, there's a good chance it's male. Not a guarantee either, though. Also, some roosters are quite late and slow in growing out noticeably male tail ornamentation, and some simply have pathetic little tails that stay baby sized.