Hey there, let me answer those questions:
1. That is correct. If there are 300 entries, then each one will get played at least once, if not more. Every entry gets at least one playthrough.
2. The "Fan Favorite" vote starts when Judging starts. Anyone who can reach the voting page will be able to vote, which is the general public.
3. So long as those images aren't of real, existing people (outside of yourself), then that is fine.