Well, I'm not against announcement threads being locked eventually.

Depending on the announcement, like says it's about the eggs currently in the shop, once those are out, lock it after a few days, etc. But that's just my thought on it :3

Announcements being locked was for the purpose of keeping things in order. For the most part, at least.

A contract with a minor is considered null. It carries no binding weight. It's not illegal to sign it, but as you say: the minor can back out at any time. Yes, that means the other party is no longer required to fulfill their obligations if the minor nullifies it, but stuff like termination clauses and penalties don't apply because the minor can't legally agree to be bound by those.

It's messy.

Edit: Disclaimer -- I am not a lawyer and my statements should not be construed as legal advice. I could also be wrong.

Well, from what I remember (which memories are faulty) when they turn 18 it becomes binding if they don't break it by then. I think.

Could be completely wrong, but it doesn't matter since the person is 18 now XD

I think that one's going to end up being a question of case law and circumstances. As I said, the contract is null, and it never carried legal weight in the first place. The contract wasn't signed by someone who had the legal ability to enter into the agreement. It would be a miscarriage of justice to pull up a contract signed by a 17-year-old when he's 25 and say "look, you agreed to this back then, you're not a minor anymore, it's binding on you because you never nullified it."

In my (non-lawyer) opinion, it's going to largely be determined by the history of the contract and the good-faith efforts of both parties. If the signer CONSCIOUSLY agrees to be bound by it after reaching the age of majority, then that's really what matters. The real challenge there is proving it, and in the event of a dispute (say, the signer agrees when he turns 18 and changes his mind at age 19) then the plaintiff would have to show proof that the signer had supported the agreement after turning 18 and then later backed down, while the defendant would have to argue that the contract was never binding and no formal action was ever taken. The only way to make this SOLIDLY binding is to sign a new contract at age 18.

Sadly, if I knew enough, I would of offered to help just for the free experience but my major is in Software/Java..