Correct.Equating humans marrying animals, with consenting adult humans being able to marry other consenting adult humans under human law is, as has already been pointed out, a strawman argument.
Correct, however you don't seem to understand that the lack of formal consent has no actual implications for the rights or wellbeing of the goat. Given the goat is able to consent in its own way (I wouldn't marry one that hated me), I don't see the problem.You've already conceded that the goat is unable to give formal consent.