Because launcher, editor, etc. use Qt. TES3MP builds linked against Qt5, so you need to install it if you want to use these apps.
Otherwise you can look for TES3MP builds with Qt4, if there are any.
The game itself does not use Qt.
Summons are followers (of their summoner) too, so "other followers" should be enough.
How about "Do not add greetings to the journal topics list"?