Reddit mentions of Hindu Culture An Introduction (The Hindu culture series)

Check out this book. It covers a lot of basic topics (ranging from vegetarianism to reincarnation to meditation to oneness and inner divinity) about Hinduism, and might help get you pointed in the right direction.

As for my attempt at answering your questions:
>Is it required to believe in a supernatural force/God?

No! I sure don't. I do believe in the the atman, the inner divinity held and shared by all people and things, which exists as the brahman, the oneness shared by the universe. I am not truly different from you; we share the same broad hopes, fears, and struggles in our quest to answer life's questions. So deities like Brahma, Vishnu, and Shiva (and the hundreds of other little-g gods in traditional Hinduism) are simply manifestations of ideals of this common atman we worship to remind ourselves of our duties and morals. I don't believe in a big-g God that created everything. The scientific method answers those questions for me. Hinduism is a method I follow to answer the types of questions that may fall outside the scope of science.

> Do most followers believe in the stories as a literal interpretation? Was it originally intended to be?

Depends on who you talk to. My mother does, my father might, and I don't. If you go to a village in rural India you'll probably find most of them believe the stories literally. Can we ever really know for sure, given the millennium-spanning history of Hinduism? Probably not. They do contain excellent, generally timeless examples of what is considered good human behavior, though. Obviously times, morals, and cultures change, but I think characters like Rama or Arjuna or Krishna are still examples of ideals to look to.

>What is the purpose of prayer?

I think this is a question best suited for you to answer yourself. If/when you pray, why do (or don't) you do it?

The fourth question I'm not going to answer, because I honestly can't help you there. I have a rudimentary understanding, but considering I don't meditate regularly, if at all, I'm just as ignorant on the subject as you.