My two pence worth is that anyone who's past using the often called 'one finger chord' accompaniment, and are playing their own fingered chords, should immediately switch to AI Fingered mode. That mode is totally 'transparent' to normal chords like majors, minors, 7ths etc, so all those can be played normally. The mode allows far more than just slash chords to be played - if you take the time to learn how, or just experiment. (A decent knowledge of chord construction helps with that!)
Slash chords do indeed have to be played. On a 61 note keyboard you'll have to set the Left and Style key splits to G2 rather than F#2, to allow the very common G/B or Gm/Bb to be played. You play the chords as they are written. C/G is spoken as "C over G", so if you think "Play a C over (meaning above) a G", that will get the chord correct. Other slash chords like G7/F will require just two notes, G over an F in this case (or F-G if you go from left to right). That will get you started!
There was an excellent series of articles in Yamaha Club Magazine, written by Jackie Marsden that explained a fair bit about AI, but really only scratched the surface. I've been asked to rewrite and extend the articles, which I will do at some point, but AI Fingered mode keeps springing surprises on me, and I've been using it since it first arrived. I don't think even Yamaha know everything that it does.
It's a mode that will do as much or as little as you'll need, so you really can grow into it. So why not use it?