How do two-day title matches work?

[sorin]

But is each player expected to be able to set up and analyse the game on a board between days?

Yes, of course. The sealed move is meant to make the situation fair, but other than that it is assumed the players can and will analyze the game without any external help during the break.

Is this a new expectation? Maeda was rumored to have found a move for Shusai in a famous game against Go Seigen, right?

I am pretty sure that was against the rules, and was perceived as very dishonorable. It is still just a rumor as far as I know, never proven.