Create a wordpress plugin for my spinner website

Hello, I need to create a wordpress plugin for my website service (http://almaqalah.com/) which rewrites Arabic articles. This plugin will allow clients to use my service on their wordpress based websites to rewrite posts, I'm going to create special API key for each client to allow clients to use the service for a fixed period of days or months.
This plugin should include these options:

- Auto rewrite future published posts. Yes/No
- Rewrite post title? Yes/No
- Words Not to rewrite. ( With a field that allows to exclude certain words from being rewritten ).

There should be a button inside the editor to manually rewrite posts and show the result before they are published.

Also there should be a Api valid or expired.