What is the value of sacrifice to you?
I cannot speak for anyone else or judge them for their feelings, but I would give my life in defense of someone in danger. Really, I would.
What would you recommend as far as learning/reading for someone looking into Hindu deities and trying to learn more about them?
I understand that Hinduism For Dummies is a good read; Hindu deities - Wikipedia, the free encyclopedia Hinduism: Beliefs & Practices.
What are your thoughts on someone who prays to a Hindu deva from outside of a Hindu tradition? (Paganism for example)
If the person believes in the deva or devi, that's fine. The Rig Veda (1.164.46) says ekaṃ sad viprā bahudhā vadanti meaning "the truth is one, but the wise know it by many names".