If I'd have to guess, someone is testing which of his accounts are proxybanned and which are free to spam.
CMIIW, but doesn't the forum show message if your account cannot make post due to evil IP, proxy ban or similar reason?
They intentionally neglect the accounts for the main time and will probably comeback someday.
Yes. Because an account, which is created today, or yesterday, is worth less, than something, which was created years ago. Also, it is then easier to abuse activity counter, because then, it is usually equal to the post counter.
This is good point. On "Digital goods" board and other part of internet, there are people selling aged account, even with very little/no activity on it.