Reservations?

"Can a reservation be made subsequent to activating a "Select Pass"" Yes
In Germany, at least, reservations are sold for point-to-point trips, regardless of the ticketing means. In some countries, like France, mandatory reservations are limited for pass holders to less than the seats on the train, so sometimes, even though you could buy a ticket, which comes with a seat reservation, with a pass, you can't get on.