We mostly used credit cards. Just even cash for public toilets, any cash tips, small purchases, museum entrances, etc. We took 200 Euros and had some left over.

I would have no idea - I sailed last November - Try Googling your question!

We went at the end of April - first of May and there were no disruptions. Anytime after that, you would have to ask the cruise line as I would not know past the first of May.

Best to ask just before you travel.

No problem now but you can expect problems in the summer. We almost had to change ship last November but we cleared the bottom by centimetres

There is plenty of water in the Danube which carried numerous sized sailing vessels

I am a traveler just like you - if you are going on a river cruise ask them.

no one can predict the weather or water for your trip! the cruise company will make accommodations to still get you to your pre-planned excursions, and will work with what they have at that time. hope your cruise is relaxing and memorable!

you will not know until you get there how the actual waters are. our cruise in Nov did have 1 day of low water & we were bussed to a missed destination. the company will work with what they have & make every accommodation possible to still get you to the pre-planned excursion (s). the busses were very nice for both the low water levels and travel to any site that was not walkable from the docks. i am not sure what your concern is as no one has control over the weather!

I would not know - I was there in November 2022.