Newbie questions

1. What is nutritional yeast and is it a must?

2. What is Tempeh and what does it taste like??

3. How do I get the nutrition I need? I'm anemic.

4. Tofu, what's the texture like? I'm terrified of it to be honest.

5. What is a must have item to always have on hand.

6. WTH is quinoa?