There is no White book on what merit can be awarded for, with a clear list of enumerated cases on the allowed/disallowed sides. If fact, there is only one related prohibition, and that is for merit sources to sell their sMerit. Having said that, there is a conceptual goal, and that is to merit decent created content.

Now a "fantastic service" to the community would qualify from that standpoint of view. We have examples of people creating tools, building bots (“good bots”), reporting cases of all sort, etc. Those are “services” to say that help the community. Now if the service consists in a translation for example, that is a personal transaction between one person and the campaign (or so), and should be paid in whatever (crypto) currency one can agree on.

For the same reason as above, it is not really acceptable. If done in the open, both parties will certainly get red DT, and merit-laundering techniques are not opaque in a system where merit TXs are logged and looked through often by many.