For those that have the game, can you play this with six players? I know you only get 4 of the fan cards, but could you use tokens for two of the managers fans? Is there enough cards to support six? If game length is a concern, could you just play four rounds instead of five? What if you bought two sets? Thanks in advance.

I suppose you could play it with 6 players, using counters or something to track fans for the other 2 players.  There's no shortage of upgrade cards to go around.  The game length would stretch out a bit, but that goes without saying.  It'd be an interesting experiment because you'd either play it pretty thin on each highlight to try and get in as many as possible or just hammer a couple hoping everyone else plays it thing.  I would suggest that you use the short seasons rule so that if you flip a tournament you only draw 5 highlights so that you never have more then 6 weeks of games in a season.

Yeah, I see no problems with 5-6 players, as long as you had dice or counters to do the fifth and sixth player.

How does it play with 2 players as opposed to 4? Is it better with more players or is the experience comparable?

The game scales well between 2 and 4 player matches.  The only difference is that in 3 & 4 player games you may thin your cards a little more.  But that will probably end up with a result of you losing all your highlights, but getting the participation award, so that's a strategic choice possibly.  However really the difference between 2-4 players are pretty minor.  The only significant difference is that it takes a little longer to play the game.  However player downtime is pretty minor since each players turn is really fast