Is there any U.S phone number to directly ask questions about the eurail passes?
According to the Eurail website, "You can contact us through email or Facebook (no phone):". RailEurope is an authorized Eurail Pass distributor and you can call them (at least you could when I did).
The Rick Steves Europe Through The Back Door gang do consultations and sell loads of railpasses. You can have a look at http://www.ricksteves.com/about/consulting.htm . They do charge for their consultations. I don't know if they would just answer a straightforward question. Alternatively if you browse around this Helpline you will find lots of answers about the passes and their value. If you have a specific question you may get your answer by asking here.