(1) I have not even finished a single game so far (but played roughly 200

)
(2) Cannot comment on that. But if you played EU3, think of these events on a smaller scale. So instead your nation get +20 prestige for it's drilled soldiers, your charater gets +20 prestige for his "brave" trait.
(3) Don't understand the issue. From a stategic POV, defence-in-depth was extremly powerful in EU3, thanks to attrition. Be warned though: Combat is at least as detailed as EU3 and has a bit less strategical and tactical depth.
In general, CK2 is more like a role playing grant strategy game.