If your in the back of the plane, and anyone else can hear the clicking on your keyboard -look for parachute! The engines have shut down.

You might be better at the front of the plane, as many airlines have increased legroom up front. (Your laptop might not open and fit between you and the seat in front of you).

As to tiring, if you are using a battery only, you might run out of juice before you get tired.

I invested in a small mouse, as I find doing serious work with the eraser point pointer annoying. Belkin makes a nifty small scroll mouse with a USB interface. I got it for $15.

Hope some of this helped!