A Crossword Puzzle Program For a Webpage

Hi,

I little birdy told me that for my next project i should try a self contained crossword puzzle project with website admin, and users side interaction of course. This would be for including a crossword puzzle page into any website, and allow that website to host its own data.

It would allow:

(not in any order)

1. Building puzzles in advance in the admin section and present them on a rotating basis or when the user requested a new puzzle.
2. Lay out the UP and Across words and numeric designations in the admin section, and store in DB.
3. Allow or dissallow the puzzles to certain users based on permissions.
4. Add the project to most any website with flexible page inclusion rules.
5. Provide an answer key in some way to assist the user if they get stuck.
6. Include a users side interaction tool such as JS for special effects with data entry.
7. Create a relational DB matching Questions - Answers - Hints, and also users to puzzles.
8. Allow the user to store their incomplete puzzle and finish it later.
9. Offer extra hints if the user gets stuck.
10. Allow the user to share their completion time with others as somewhat of a bragging tool.

This would be coded using PHP, Curl, JS, HTML, MySQL, and CSS.

I already have the code structure in my head (much like a contractor sees a house before he builds it). What i am wondering is since i have never built one of these before:

1. Is there anyone who plays these puzzles religiously who could add to my needed features list.
2. If you have built one of these before - what do you wish you would have included that you did not.
3. Any other content or coding suggestions that might be beneficial in the long run.

Thanks :)