If you haven't heard many of them already, start with his piano sonatas and fantasies. All beautiful works and a great way to get into his music.

His 41st symphony is one of the easiest things to get into when first approaching his work, and it's bloody fascinating if you get a good performance of it.

That's one of my favourites. I love it.

I like quite alot of his symphonic music, even quite a few early ones that most people ignore.

No. I read (I dont remember where) that it is the tempo, rhythmic accuracy and style of the piece which is important. Pieces of moderate tempo, with repeated themes and rhythmic precision i.e. most stuff from the Baroque period, Bach, Scarlatti etc. and classical period like Mozart would have this effect. I personally believe listening to any music is good for your brain and playing/composing is even better but when Im studying I much prefer silence. Its worth bearing in mind that youre more likely to recall something if the environment youre in is the same as when you were learning and since expected to be silent in exams...I also think that if a person is feeling the need to use brain tricks to improve learning theyre are probably not reaching the meaning very well which is the most important factor in learning anything - understanding.