That sounds cool. Well, Xavier could have been a guest lecturer at a school or conference Tony attended, or they could have met at fundraisers, or lots of things, really. Or Xavier could have gone to Tony's school twenty years before and come to an alumnus day or something. Lots of ways! And as you say above, Tony attended the Hellfire Club in his younger days, so there's definitely ways the connection could have been formed.

Ult Tony is much more practical than 616 Tony, I think - there's indication he has some kind of mental issue, Jarvis referencing his black dog, but it doesn't seem to have ever concerned Fury. Probably depressive issues, given some of his behaviour.