That first map showing the wye and route to the PRR is interesting and probably pretty close to actual. As Russ said, the creek has wandered a bit. The track was poorly constructed, so I doubt if anything could be found there today. Also, several major floods have had there way with the land through there. The BA&A did have a wye in the location of the parking lot that may also have come before the extension to Arcade Junction. The narrow gauge planners had two routes surveyed when they passed through Arcade. For them, one route was on the north side much where the Borden's siding ended up, the other was the south side much like the BA&A built. They only proposed the routes to try and keep the Springville & Sardina and investors from that area hoping for that narrow gauge connection happy. With the Erie people involved in the TV&C, we know that they instead headed south towards Cuba.
As for the BA&A, they at first did not originally cross Main Street. It is logical that they'd have a wye located on the south side of the creek, as there would have been a need to turn locomotives for the return trip to Attica. The first Depot was in the building that is on the North West side of Main Street with the loading platform on the west side of the tracks. (It was known as the Railroad Block and had Rosier's Hardware more recently) Today a block addition was added where that once was. The current Station was purchased in 1900. The south leg of that wye lasted until the 1960's. It was utilized to unload coal and the Grover Cleveland Car was stored there at times. Once the B&S was firmly in place and the current wye was constructed, there was no more need for the structure at the bridge.
I finally saw one picture that showed the north end of the wye in place, though I don't have a copy of it yet. I have seen another picture of the Merrell-Soule & Co. milk factory and it shows the BA&A right of way crossing Church Street (just south of the road bridge) going behind what is today the Elementary School.
As for the switch on the bridge, it was indeed on the bridge.
The south span carries not only the main track but also a wye track. The switch is located on the bridge at the pier, and the frog is about 5 feet north of the south abutment...."
From the Second Annual Report of the Public Service Commission, Second District for the Year ending Dec 1908, Page 708, New York State Archives