Hello,
First of all, thank you for your purchase.
1. Yes, category filtering is possible in the plugin, please check this video for details: https://www.youtube.com/watch?v=WxCLG7xM8_4&list=PLEiGTaa0iBIhKwBdxZMUdHHY4XuXLvctE&index=30
2. Yes, this is also possible, please check this video for details: https://www.youtube.com/watch?v=zWqz6a8yuHY
3. Please replace wp_cron with server side cron (this sounds like an issue with wp_cron on your server, which is a WordPress module which is used for rule auto running). Please check details on how to do this, here: https://www.siteground.com/tutorials/wordpress/real-cron-job/
4. Yes, you can link to the source, please check answer from point 2 from above.
Regards, Szabi – CodeRevolution.