Is there any way for me to get notified of any post by a certain user?
Look in your preferences under “notification”.
You CANNOT track a certain user, although you can MUTE users.
What I do is have the forum send me an email for every post, so I can use Mail rules to my heart’s content to manage them.
I also have an AppleScript to open the current topic from Mail in Safari:
I write all my posts on the forum using Safari, so I can see how the Markdown looks.