You're probably better off posting those questions separately. It gives you the chance to pick a good title for every one of them, and it reduces the scope for a proper answer somewhat.

For the Dark Ages, you can also check ou the FAQ on that topic, though of course you are always welcome to ask your own question and hope for a new answer.

As edXcitizen87539319 said, you have many, many questions here, not just one. You'll be better off posting them separately.

As for reading material, you might enjoy browsing our book list.

Thank you.