So here’s a response for each item you brought up
I think you mean the ability to set the vertex radius? You can set it here in the Sidebar:
It might be possible to add as a shortcut also if you have a specific suggestion that doesn’t conflict.
Not sure what you mean exactly. You can find all the Mask operators here:
It’s also possible to improve the Mask tool:
Is this the bracket issue with German keyboards? Any concrete suggestions?
Yes, I generally didn’t alter modal keymaps since modal operators is mostly a Blender concept anyway. It would add a lot more changes, but if it makes sense it could be worth it. How exactly would you change them?
That is absolutely true, and one of the reasons I looked at adding keymap prefs to the IC keymap - to make it much easier to make common tweaks.