In the novelizations (Lord, the more I write about The Ultimates, the more disgusted with myself I feel. I have monster issues with the writing, but I keep on reading). Yes, Tony's always in constant pain. When he first tasted alcohol, it got rid of his pain. Of course, that was written after The Ultimates (Ultimate Iron Man came out after the Ultimates), and Tony has well... health issues, so his boozing for good or ill is moot at this point.

But Tony's personality in the IM is interesting. He's mercenary, shallow (he fell in love with his fiancée, because she reminded him of himself - with tits. No joke), his relationships with women are fleeting,and doing this superhero thing because he's found a sort of 'religion' - more to do with his own sudden mortality(Tony is still an agnostic/atheist in this version) than anything else.

You get the feeling that he's hosting The Ultimate Avengers as a mixed bag. Yeah, he's making mad money out of 'em, but he's also actually establishing relationships - helping Cap out, running interference on Pym, etc. It's been interesting watching his character develop in The Avengers.

Which is why I think he and Steve will be relatively close if the series goes on, because Tony is just chill to Steve's intensity.