Ruy Lopez Berlin Endgame Questions?

Ahhhh the opening that helped Kramnik defeat Kasparov. Im thinking of adding it to my 1...e5 rep because i play the Classical Ruy (3...Bc5) and the Berlin (3...Nf6) but what im wondering is...keep in mind is, if i study the positions a lot will it still be extremely drawish? I mean im not playing Carlsen so with good endgame study could i make it a really mean weapon or could just anyone hold a draw or even win against it against me? 

Also how forced is this line after 4...Nxe4 is there a lot of possible sidelines for white?

5.Re1 and 5.Qe2 are interesting sidelines.  I think 5.Qe2 to be very strong but that's just in my personal AN.  The endgame leads to play with mutual chances to outplay the opponent, probably White should have a small edge with perfect play, but often Black has the easier time of finding a plan and has long term trumps.