Re: Superman's power level - Part 1
Regarding intelligence; there are plenty of different kinds of intelligence. I might be able to solve an incredibly complex mathematical equation (I can't but anyway), and then have no clue how to position myself and/or troops on a battlefield.
Superman may be able to learn languages and/or grasp high level scientific fundamentals in the FOS, but Batman can easily be on the team based on just being better in resolving how to target an enemy best, and take him/her down.
Does odd things at random times.