(1) I did a Google search. There are five Auburndales in the US. One is a neighborhood in Louisville. Seems unlikely. One is a neighborhood in Queens. Seems unlikely as it is well to the east of Sunnyside. One is a town in Wisconsin that is on the wrong railroad line for Amtrak to be interested. This leaves two candidates:
-Auburndale, FL (presumably associated with the Silvers, potentially part of a potential joint project with Florida, and the obvious candidate)
-Auburndale, MA (a town on the Framingham-Worcester line; I think MA owns this track, so that would eliminate this as a candidate, but I'm not entirely sure on that front).
(2) 2nd Ave yard in Seattle would be a bit south of King Street. 2nd Ave terminates in Stadium Place. 3rd Ave terminates at the station but resumes a while further south and parallels the yard.