can you get the Systray to the popupmenu?
If yes, how to do that?

no, you cannot... only if you are a programmer ;)

no way to get a list of running systray apps in the popup menu, like there is for running tasks, eh?

I have not actually tested this, but I would assume that with some extensive scripting you *could* get the systray to snap to the bottom of the popup, when !popup is launched (and obviously disappear when the popup does). I can't say for sure that it IS possible, but it's an interesting idea, at least ;)

take a look at Smurth's skinbox-themes for scripts that does "snapping".