Playmakers are good for creating more chances for the team, unfortunately all your passing have to go through them...also not every chances created will produce goals. This would also depend on the finishing ability of your strikers & fellow attacking players. Playmakers however do take good freekicks & corner takers and I tend to prefer them over those with those respective SAs.

I've never had dribblers so I don't know wht they are good for.

There is no right or wrong formations that suits SAs. Treat them like your other regular players.