Caution. *Sein sollen* has some tricky meanings. Same with the other auxiliary and modal combinations. > Wenn es nötig sein sollte. is simply another way of saying > Wenn es nötig wäre. --- 1. All the occurences of *wollte* in Kafka's text can be replaced by *würde*. You lose the intentional aspect that way, however. That had to be guessed then. For the first *wollte* it's obvious because of *ja gern*, for the others not so. It would read as if Karl had a lucid dream instead. 2. Same as 1. 3. Not without a drastic change in meaning. If you write *wollten* you imply their intention is not successful. (And it's much more common to write *wollen würden* in that case, because *wollten* could also mean it's past tense.)