Sorry for the delay in the response.

Thank you :)

Your welcome 💐

5. What I meant by that question was rather “what’s the design vision?” Is the intended usage more like everyone should have their own, or rather those should be shared with more people (to lump up different topics originating from the same machine)

The design vision for the websurfx engine is to protect user's privacy, and to have a really secure and fast search engine along with that also provide a really customizable, safe (like the level of protection you want for the safe search to go even allowing you to use filter lists to filter out specific websites from the search results), highly theme-able, and with organic and ad-free search results. So that the user can get a search engine which is entirely their own.

And for the case whether you should self-host it or use an instance of it depends on your threat level. Like many people because of your threat model may prefer self-hosting as they may not want to have their data served from a computer that is not their own.