1. When to use the section tag?

2. Are aria check-boxes different than the normal button semantics and which should I use?

3. Should I always add a copyright like bar to the bottom? What is the right tag for this?

4. What are best practices for top bars and nav bars? Are nav bars nested in lists usualy? Are top bars any different from the normal layout of the rest of the page?

5. When should I use class for my CSS and when should I just select by some other attribute or some other more specific selection? Should I avoid giving things a class?