I don’t typeset music myself but I’ve heard that LilyPond is very good. It is based on LaTeX.

Great job!

I use Liberapay and have been pretty happy with it. Have found quite a few of the people and projects to which I would like to donate, but not all.

I use Runbox, and have for many years. Overall I’ve been happy with them. I think they have the features you are looking for.

Spångest intensifying…

I suspect that the Belgium-Netherlands border defies any mathematical description.

Really? How does that play with jurisdictions that have right to right to be forgotten laws? Seems like a pretty risky play for them to restore deleted posts that were explicitly deleted by its author.