1) I assume I would have received an E-Mail notification if the hacker had changed the E-Mail address or password on the account, and he didn't want me to know that he had access to my account.
You would not receive any kind of email notifications sent by the forum when you change your email nor when you change your password.
3) I hadn't logged into my account since last July and E-Mail notifications are not sent when a hacker posts a message using my account. I found out somebody was using my account when I received E-Mail notifications that my account had new private messages from you to the hacker.
So let me get this straight, you were willing to access your account after ~a year because someone was randomly PM'ing you, but you were not willing to access your account when theymos emailed you when the forum was hacked?
@OP -- how many PM's did you send this person, and when was the first/last PM that you sent this person? When you accessed the account were all of the PM's you sent this person still in his inbox?
I would say that based on what I have read so far that it is more likely then that that the person who the OP sent the loan to is the same person who created the "WhitePhantom1980" account.
I did find an address posted in 2013 by WhitePhantom that is a btc-e address