Michael,
The LHS button only work as AEL if you set it in the custom function. I forgot which number.
Yeo,
For battery consumption, it really depends on how you shoot with the N1. If you shoot few rolls continuously (say 5-10 rolls within an hour), the battery may go dead in about 5-6 rolls. But if you turn the camera off and on (perhaps a few times), the battery level will go back up. I don't know why, but that also stated in the owner's manual. If you shoot casually, one 2CR5 will last over 10 rolls easily. I shot a wedding with the N1 for 10 rolls of films in 8 hours without changing the 2CR5. As Taylor mentioned, also keep spare battery with you.
As I mentioned earlier, if you don't use the AF all the time, the battery drains quickly. It takes a lot of juice to move the heavy Carl Zeiss glasses (with metal barrel).
I don't use the P9 since it adds weight. But it seems to be a good economic and flexible option. If nothing else, it makes your N1 outfit looks more professional.
