1. Keywords and spaces.
2. Numbers (0-9), lowercase letters (a-z), uppercase letters (A-Z), the dollar sign ($), and the underscore (_).
3. CREATE DATABASE yourschema;
4. The Output panel.
5. With a natural key, you are using unique columns, and the data in those columns exists outside the database (that is, in the business world). With a surrogate key, you are creating a column to hold a unique value for each row, and that value isn't used anywhere outside the database.

6. # this is a single line comment
7. /*
   this is a
   multi line
   comment
   */
8. Clustered indexes sort the data in order on disk and nonclustered indexes don't.
9. If two or more queries are requesting the same data, creating locks that won't be resolved, MySQL will decide which is easiest to kill (usually based on how long it will take to roll back any given query).
10. Yes.