All those things are good to have but they won't save you if you have no indexworthy content and no links.
If you're selling you should have refund policy, tos, return policy because they are important to your visitors. As a buyer (in general, not just domains) don't you avoid sellers that don't disclose who they are and their policies?
Everything is relative to your vertical. What are your successful competitors doing? By successful I mean ones that rank well for hundreds of topic relevant terms. What kind of links do they have? What kind of content? What kind of sites link to them? How do they link?
Do at least that, or do better.