Lame endgame?

[Nate tha' Great]

Last night I made it to the final two of the Party $100+$10 MTT buy-in. I had quite a substantial chip lead over my opponent, roughly 2.8:1. However I was pretty exhausted and my opponent seemed solid. I have not played a lot of tournaments lately and am not all that confident in my NL heads-up skills.

In two of the first three hands once it was heads up, I received AKs and JJ and pushed before the flop both times. My opponent folded both times and I did not show him my hands. At that point my lead was up to better than 3:1 and I resolved to either push or fold every hand that I played.

(1) How much am I giving up by adopting this line against an opponent against whom I probably have a slight skill disavantage?

(2) Assuming that I do decide to play this way, approximately what percentage of my hands should I be pushing with?

(3) If my opponent doubles up and the stacks pull to about even, do I need drop the strategy and start playing poker?

(4) Was it a mistake not to show him my cards when I went in the first couple of times with big hands?

-Nate