@1. Hardly ever-in most cases it will be CHANgeable to other train, but only if done before original has left-so they can in theory sell that seat again. IF allow payback, there is also most often a substantial fee for handling to pay-leaving very little for you.
The DB/german INland RES for 4,50 are lost when you do not turn up. Many bisnispeople unsure what time their oso imprtt meeting ends or how long the saufen afters last-make several such RES just to cover that
@3.alas-word of warning-many seats that are non-aisle will not have a window beside them-it may simply be you hit that seat right beside the wide stills (metal). On hi-speed lines most views are marred anyway by sound-shields along the tracks.