-(RP) Tasteful fourthwalling is a go! This version of the Doctor is not very good at fourthwalling others, however, unless someone happens to be from a book he loves, or a film that Peri or Tegan may have forced him to watch. He will fanboy at historical figures like a mofo, just FYI.
-(RP/Fic) Crossovers are go! Personal retcon arrangements can be made if a muse would like him to have visited their world. The typist makes up many worlds and events this Doctor has attended, and having been somewhere otherwise established is no problem.
-(RP) Sexual and romantic pursuit is a go, but is a bit of a touchy subject and might end in a wild goose chase. The Doctor finds very little use in such pursuits, and is usually oblivious or dismissive to such advances. While the typist currently engages him in a few different relationships of this approximate nature, those involve specific circumstances in their particular strings of fanon/reality. He is still the Doctor through all of that, and will still act as such. If a muse would like to be romantically or sexually involved with him, prepare to put a lot of effort into CR first, and expect rather a lot of rejection/brushing off, unconscious neglect and frustration. You might be handsome/pretty and a very amazing lady/gentleman/what-have-you, but there's a whole Universe to pay attention to, and it's much more interesting than kissing.
This all pertains to both fanwork and roleplay.
-Death: None for me, please. I didn't make a Fifth journal to play the Sixth, and I write regeneration scenes pretty terribly. If you want to involve him in someone else's death, it can be discussed, but there's got to be a good reason for it.
-Injuries / Torture / Violence: Possibly. Again, discussion and good reason. This Doctor will NOT willingly inflict pain on someone else. (...okay, maybe Davros. MAYBE.)
-Mind control: not on him, thanks. There are a scant few he may take empathic liberties with, but ONLY with their permission, and never to manipulate them. He expects the same courtesy.
-Sexual HELL NO's: Rape/non-con. Children (in running with American laws, where the typist currently exists, 18+ is the bare minimum of acceptable, though we much prefer at LEAST 21+). Necro. Snuff. Excrements and unconventional fluids. Bestiality. Gore. Vore. Feet.
Anything I haven't covered that you'd like to know? Ask!