You are right about tactics, but probably the only way to begin learning them is to be given problems where you know what theme is there, and first learn to spot it, followed by problems where you know
some theme is there and have to figure out which one. The theory is that if you do this enough sooner or later you will be able to spot when tactical themes exist in your own games, both for and against you. In my case it remains a theory, at least spotting tactics against me!
As for the historical info I've seen it a few places, but the following link to an interview with Kramnik covers it pretty well.
http://www.kramnik.com/eng/interviews/getinterview.aspx?id=61