UX for self service [on hold]

I'm currently designing a help page where users can essentially service themselves; help documentation in the form of articles, FAQs and so on. There will be information about the workflow of application with schemes, screenshots, glossary, and information about each integration system.

I have got some questions: 1. Are there any best practices I should follow to design helpful self-service page? 2. Which elements should be on this page? 3. Should it be on another domain, if there isn't a lot of information?