You mean Plasma 6.0.2, not 6.2 - that will be released in a year.
Use X11 to Wayland Video bridge to get screen sharing working with any X11 app that can’t talk to desktop-portal/PipeWire (such as Discord)
What’s worth noting is that applications, as of now can’t affect window positioning in any way. It’s all about how compositor (kwin_wayland in this case) is placing them. Personally I don’t care that much because I’ve got shortcuts to quickly move windows between screens or desktops. You might consider looking at window rules - they’re pretty neat on KDE.
Shutting down? What???
On the tdrop thing, I wouldn’t expect it to be possible in near future, but how about Yakuake?