I understand the situation now. It looks like I'll have to either keep using Mixmeister or continue looking for different software.
I haven't read the whole thread in detail, so perhaps I am missing some specifics that won't make the following an option, but I thought to share this anyway.
If I understand correctly you are aiming to create a playlist for a set, then start that playlist, and have it stop after every song, and be able to simply start the next song which will also stop after it has played.
I believe this can be done with the use of just two shortcut keys.
And if you use the (free) AutoHotkey software, you could achieve it by using only one shortcut key.
First you need to create two shortcut key combinations in MusicBee.
One for "Playback: Play now"
One for "Playback: Stop After current"
Let's suppose you assign F9 and F10 to these two shortcuts.
After you have created these, selected your playlist, and make sure all the tracks are displayed in the 'Playing Tracks' pane on the right.
Also make sure that the (Windows) focus is on that pane, and not on the main panel. That's important!
Then press F9, and immediatly after that F10.
The first song should start playing, and stop after it is finished.
When your audience is ready for the next song, just do the same: F9, F10.
If you install and setup AutoHotkey, you can rather easily create a single hotkey that will perform: "press F9, short pause, press F10"
Hope this helps.
edit:
And in case you have a keyboard with some additional programmable 'gaming' or 'macro' keys you don't even need AutoHotkey.