Can’t offer support in this thread! Hit up our support team.
Yes, this is a good summation.
Deprecating something means you’re getting ready to get rid of it. We don’t want to do things in half-measures or in “willowy” ways. We’re getting rid of it.
SDK2 served its purpose and let people create some cool stuff, but keeping it around and letting users continue to upload it offers very little return for potentially quite a lot of investment. Supporting something doesn’t just mean working on it directly, it also means including it in QA testing, integration testing, ensuring there aren’t security regressions or knock-ons from seemingly unrelated changes, etc. You can’t just have a thing in your application and leave it to rot.
Our testing suite already includes SDK2 worlds and we want to remove it, considering how little of the current, populated, and used content in VRChat is SDK2 (very, very little).
Also correct!
Lol, as an amateur programmer, JS is a complete nightmare compared to C# (and its subset we have in U#) regarding synchronicity and dependency hell. It’s gotten better but there’s a good reason why I’ve swapped entirely to Python from JS. 
I’m surprised you feel that way, but understand what you mean.
It’s a known issue, it has to do specifically with the TrackingState state behavior. It specifically affects Index users.
We know about the bug and tried to fix it today, but it goes deeper than just a one-line fix. Since we try not to push Friday or weekend patches, it’ll have to wait until Monday.
I covered it a bit in this thread on Twitter, if you’re curious.