> Is it correct to say that the Museum pass gives you access to ALL the museums in Berlin?

No. "Only" 70, the state owned ones and some of public foundations.

The most important ones are however among them.

Here the list:

berlin-tourist-information.de/international/…

Berlin Museums

berlin-tourist-information.de/english/sights…

> Is it true that no museums open on Mondays

No. But most.

*The Jewish Museum Berlin is open on Mondays from 10 a.m. to 10 p.m.

juedisches-museum-berlin.de/site/…

and for the state (Berlin) owned ones:

Following houses are always open on Mondays:

Friedrichswerdersche Kirche 10 - 18 h

*Altes Museum - Antikensammlung 10 - 18 h

*Altes Museum - Ägyptisches Museum 10 - 18 h

Gipsformerei 9 - 16 h

*German Historical Museum

http://www.dhm.de/ENGLISH/index.html

* these museums are among the most visited/important ones in Berlin

The break even point of the Museumspass is easy to reach. Already with 2 of the major museums. Or latest with 3 ones (thus with just one per day).

Welcome Card is more tricky.

Depens on your schedule. The welcome card includes 72 hours free local public transport. Thus maybe 0,5 + 1 + 1 + 0,5 days. Thus one question is if you safe 3 or 4 day tickets.

A day ticket for Berlin (zones AB) is EUR 5,80. For Berlin + Potsdam (zones ABC) EUR 6,00. The Welcome Card is valid for zones ABC.

Museums: depend how many - but with 3 or more the Museumspass will be the better deal as the Welcome Card gives only (small) discounts.

If you qualify anyway for a discount (e.g. as a student) the Welcome Card makes no sense, as you cannot add the discounts. But the Museumspass exists also in a discounted version (50%).

Other sights, city tours, theatres etc.

Depending on your plans the Welcome Card can be a good deal - or not.

I recommend the wellcome(48h or 72h) card, you get 48/72 hours transportation card for the 3 zones(a,b,c) and reductions on prices of museums(some up to 50%), it depends on how much museums you want to see, but in berlin the are a lot of monuments and places you must visit that are free, so if you are for a short time I dont think the museum pass is a great deal.

We bought the 72hr welcome card but hardly got our money's worth even with our son travelling free and our going out to Potsdam. We didn't use many of the discount vouchers, and one we would have used, for Märkisches Museum wasn't necessary as it turned out to have free entry that day (Thursdays, I think) in any case.

Info on Berlin Welcome Card including discounts and partners:

berlin-tourist-information.de/winterzauber/…

3-day "Museumspass"

With the 3-day "SchauLUST-MuseenBERLIN" ticket you can visit more than 70 Berlin museums and collections on three consecutive opening days for € 15.– / reduced € 7,50. You will have access to the famous buildings of the Staatliche Museen zu Berlin – Preußischer Kulturbesitz –, including the Pergamon Museum, the Egyptian Museum and Gemäldegalerie (Painting Gallery). You can also visit the museums of the Stiftung Stadtmuseum Berlin, the German Technology Museum, the Brücke Museum, and many others.

Follow the link "SchauLUST 3 day museum ticket" on the right to see a full list of museums covered by pass:

berlin-tourist-information.de/deutsch/sights…