Ketsuen, I like your ideas a lot
Actually what I was going to do is from everyone who joined, I'd take those I know would be good owners and I'd let them select their GM and manager. I wouldn't make them suggest to me, I'd let them hire whoever they wanted from the available pool of guys (see what I mean?). That way the pitching/offense style would automatically reflect those of the owner, as the owner would choose someone who shares his vision. I hope you understand what I'm trying to say
As for manager attributes, I was juggling with the idea that the managers would setup their profile, and it couldn't be edited afterwards.