My understanding is that you need to pull offers from hasoffers and show them on your site.
Hasoffers has two APIs i.e Affiliate and Brand. My assumption is you need to get offers from Brand API
Please see my response inline.
1. Create catalog plugin. OK
2. Connect catalog on website with offers catalog from has offers. So i will pull offers from hasoffers via API and put them on website.
3. Add some custom fields for offers. Yes sure i can add, please explain which fields you need.
4. Move statistic information from has offers to website. OK
5. Connect category for offers. I am not sure if has offer is sending category with offer. If it sends i can match it with Wordpress or Woocommerce categories
I also assume you already have a wordpress website that is showing catalog. So my task is to integrate hasoffers API and NOT to build a whole wordpress site from scratch.
If there is any question, feel free to ask.
Regards,
Kamran