My issue is the following:
I have my MBP, Apple TV, Airport extreme, and a WD My Book external HD that I'm trying to get to play together. My goal is to have my iphoto library entirely on the external drive upstairs (referenced library) connected to my aiport extreme. I would keep my itunes library on my MBP.

Would I be able to access that drive and iphoto library on the apple tv and MBP when connected to my network?

Would this also mean that I would not have any photos on my MBP if I am away from my home?

Lastly, would I be able to access that drive remotely? say from my computer at work or anywhere else?

This all makes sense to me in my head, I'm just not sure if everything I've talked about above is actually possible.
Thanks for taking the time to read and help me out.