You almost had it. Wild Child was played briefly by one other person, and X-Factor did indeed happen. Cut-off point, specifically, is around July '95 to August '95. Chris's (H Psylocke) Aurora's application left it up for interpretation, so I went to an older one, and like Chris pointed out, they did indeed have a relationship that played over to neXus.
I'd say the best cut-off point would be after Wild Child reverts back to his "ugly" appearance and runs off, leaving Aurora.
The Weapon X at neXus was started up by Malcolm Colcord who used Copycat as a perfect example for Weapon X to start up stateside. Through a lot of drama, Weapon X ended up being blown up by Sinister. Wild Child's whereabouts have been unknown for quite some time, so what he's been doing is up to you.

For board history and Weapon X, I went back and read an older thread to make sure, but Wild Child's capture into the Weapon X program was never specified, which leaves running away from Aurora to be the perfect moment for board history to start.
http://s9.invisionfree.com/nexus_rpg/index.php?showtopic=65&st=78Above are the four threads Wild Child was apart of at the board. If you wish, a staff member can PM you a collective summary of the threads above that only pertain to Wild Child.