It won't have much use as there are no platforms for those tracks on any of the stations on the line up until Coney Island.

Yes

It ran via crosstown which is is via the G line where it avoids all Manhattan from Bergen street to court square and via the E to Jackson heights it avoids all Manhattan

I just assumed that they permanently changed the chime to that standard one (so I never went to that car again lol) Ima try catching 5074 when I have the time

@@MTAGuyAndrew the chimes changes by themselves because of the weather

It's a glitchy ad LCD screen. Aka a Broken or shorted Ad screen on the MTA subway.