OK here’s what I remember about the use of the Eurail pass.
The first time we used the pass was in Prague. Upon arrival at the train station we go a porter to assist us from the station entrance to the train , we previously had stopped by the station to inquire if reservations were required and was told on the period we were travelling (it was Easter week) that reservations were not necessary ) so the porter loaded our bags in a Ist class compartment … this about 10 mins before departure .. then we discovered that the pass was required to be presented and stamped at the ticket office before the first use… so it was a mad rush back to office and without the porter I would not have made it ( he cut into the line and got it done explaining frantically to the agent in Czech) or else my wife would have sped off to Vienna on the train without any tickets without me.

All subsequent use of the pass did not require reservations but be forewarned that the 2008 European Football (soccer) Championships are being held in Austria and Switzerland in May/June 2008 and all game ticket holders will be able to travel on most public transport including trains free of cost on all game days.( Suggest you also lock up your hotels as soon as possible because fans may actually be booking up hotels in the neighboring countries like Poland /Czech Rep/Hungary) so you might have to make some reservations for trains.

So since we didn’t make reservations for the days we travelling I am not sure if specific seats were assigned when they a made, during our entire travels we just boarded a First class car selected a compartment and that was that. We never had to share a compartment and they only minor disturbance were the authorities (customs/immigration) who checked and stamped passports when we crossed borders.

I am pretty sure you can buy tickets at any location or on the Eurail site.
Check out the Eurail site there is tons of rail options given including cost for an extra day(s) to be added to you pass, single and multiple adjorning country passes and discount passes for more than one pax travelling together. I believe the site will address just about any question you may have.

http://www.raileurope.com/us/rail/pa...opean_pass.htm

We did not take any overnight trains so I cannot help you there but I do know that a single day of the pass incorporates the overnight train (I think it starts at 1800hrs) and all the next day use of the pass.
Hope the above helps PM if you think I can help further or some restaurant recommendations.

mike