Switched to Sublime Text years ago. I just have my configuration, and it works fine for me, so no need to change it for the rest of my life. I don't even care if it's not updated ever again.
I don't know about that. I think the visual programming aspect is the most defining trait, in which case...? I don't know any general purpose non-toy visual programming languages/interfaces. Scratch exists but likening PD to Scratch doesn't seem fair to me.
My only knowledge of PD is from graphical interfaces that implement components using it, so my assumption was that Csound was lower-level due to my (brief) experience writing on it.