roberttx wrote : Even when I win at the casino, I can't get anywhere with her friends.
You have to kiss her immediately after winning, which will increase RACHfun by 1.
I believe you only need to increase RACHfun twice for the leisure centre ending (and no drinks at all from what I can tell). There are three other places where you can increase RACHfun (and for the leisure centre ending you'll be doing one of them anyway), and another where RACHinf is increased. Unfortunately RACHinf isn't tested anywhere in the game. I assume it was intended to be RACHfun.
Fun 3 is only needed for the two Rachel solo endings (the one at the hotel also requires 3 Drinks). And, apart from getting Rachel to flash you at the store, that's all that the drink and fun stats are used for (although you still have to get other people drunk and gain influence with them).