Backdating: I'm totally fine with it.
Threadhopping: I'm totally fine with it.
Fourth walling: Making minor offhanded Harlan Ellison references or something is okay. If your character literally has read or played IHNMAIMS then... no? Don't tell that to AM?
Offensive Subjects: I get offended by almost nothing these days, so go nuts.
Hugging: Go ahead. AM may or may not appreciate it.
Kissing: Same as above.
Flirting: Please do. AM may flirt back in an effort to manipulate your character.
Fighting: Sure, go ahead.
Injury: Sure it can happen both ways.
Death: Sure, just ask me first.
Telepathy/Mind Reading/Mind Control: If your character can read minds, then go ahead and read AM's. If they're reading a plot-important thing, though, just ask first. Same thing with mind control; give me a heads up.
Hacking: If your character is good at hacking, then go ahead, unless it's marked as 100% unhackable. Depending on what information you want to hack, just ask first.
Other Note: AM is a vicious, sadistic villain. While I always make an effort to talk to players OOCly before he does anything violent or upsetting, he is still very creepy and unpleasant. Please feel free to opt out of any interactions, or specify what he can and can't do.