1. The summer timetable should already be in the planners, except for the Italian one. Italian railways are always late with that. They have just published the summer timetable for long distance trains on their own website and it will take some more days for it to appear in other planners. For regional trains, it can take another month, based on experience from the past.

The consequences of engineering works however are not always published many months in advance.

2. Which exact train to Berlin do you mean and on which date? There is no direct night train Amsterdam - Berlin but there are some possibilities (seats only) with a change.

@rvdborgt I saw a train on the website that leaves on the 28th of July, 22:34 Amsterdam Centraal and it will arrive to Berlin HBF (tief) at 5:52 (i think the reference is IC415). 

And thanks for the quick response it was really helpful. I will try to rescheduke things because if no more trains are going to be published I should probably change things :)

It looks like the train from 22:34 until 5:52 is the one that has been postponed again. It will not run this summer. @Nanja, it should be removed from the timetable for now.

There is this possibility (seats only):

Booking seats is best done via DB (click on "Seat only”); that's 4€ per person. Interrail charges 2 x 8€ = 16€ per person.

@rvdborgt if I have an Interrail Pass, can I also reserve a seat via DB and still make it part of the pass? Or I can only do it via Interrail?

You can book a reservation anywhere you like. There's no obligation whatsoever to book a reservation via Interrail.

Reservations are optional, by the way, for the connection I posted. Same for all day trains in Germany.

@rvdborgt, we cannot find the train in the timetable anymore, so it is probably removed from Merits. I you can still find it, please do share the details so that we can add the attribute to it that is is not included.