1. Composition of an orchestra: I already know the set-up by looking it up, but my sounds on my workstation should match. I'm not saying it should be very realistic though. I want to use some old romplers beside my Yamaha MO8.
2. How to play each part. Strings and brass play very different than piano. I should develop the right technique to make these instruments sound good. Some basic knowledge like which kind of chords to use, etc.
And that's it so far. Does anyone know a good source for this kind of information?
Everything else I will gradually learn by listening and listening and listening more. The style I'm going for is the e.g. the soundtrack of Super Mario Galaxy and this nice demo.