1) These scam attacks are happening everywhere, there's been a case over on Sonic Retro. We're just another random target something chose to attack.
2) It's most likely a bot, all the accounts who have posted spam were accounts that have existed for some time under a real user (EX: SolidSonicTH).
3) Maybe
What I don't know is how they even accessed the accounts. I might've been a brute force attack on the hacker's end, targeting accounts who have been inactive for a certain period of time. Maybe they got a fake email and gave their account information to a shady character. All I know is that it seems the email addresses for the hacked users have not been changed. SolidSonicTH's email contact is still seems to be their original email.
Just remember, hide yo kids, hide you wife, hide yo husband because the boogeyman is coming for your account ![Wink ;)](./images/smilies/icon_e_wink.gif)