Does anyone know anything about parking at Poughkeepsie's Amtrak station?

On the availability question, I'd say yes, but that's based off of my limited experience with this station. During work hours on a weekday, parking will be hard to find if you aren't there early enough, but every other time you should be able to get lucky. With price, I don't recall exactly what it is, but I can tell you it's not too bad. You can park for either 16 or 24 hours at a pay station, and I'm about 99.9% sure that the 24-hour parking is about $4 or 5, at least last time I was there it was.

24 Hour parking was $4 last time I was there, which was about 6 months ago. I didn't have any trouble finding a spot, but that may have been an off day. I was there once on the weekend too, and there were plenty of spots then.