I think they're re-doing the parking lot, but I didn't stick around long enough to investigate -- I was trying to cross the street without getting killed. Those didn't look like curbs on the ground, though - more like foundations for kiosks or something. I'll probably be back in a couple of weeks, or I might just drive past it one day.

The bike rental that I saw near the tennis center was actually a trailer, if I remember correctly, and it was on the east side of the circle near the base of the subway ramp.

I looked at your description of Valhalla to Bronxville and I'm anxious to give that a try one weekend soon!