Prague tap water, transit pass validation, operability of downloaded Google Maps

I can only comment on a few of your questions.

I drank tap water a lot in Prague and didn't notice an odd taste or have any ill effects.

I don't often drink sodas, but I've most often had them presented in a can, with a glass on the side. I Googled for info on can size and found this from Wikipedia: "In Europe the standard can is 330 ml, but since the 1990s 250 ml has slowly become common, along with 500 ml." 330 ml is about 1/3 of a liter and thus close to 1/3 of a quart (11 ounces). A 250 ml. can is distinctly small, about 8.5 ounces. A 500 ml. can would be about 17 ounces, but I don't remember ever seeing one of those in a restaurant. Menus in Europe are often more detailed than ours. You may find the Prague menus specify the size of the soft drink, removing any doubt about how much you will get.

I walk a great deal, even when it would be faster to hop on a bus or tram. In a city as gorgeous as Prague, I like to take my time. I think whether a pass will be financially helpful will depend to a considerable degree on where you are staying. Is every day going to begin and end with a substantial commute to your first sight, or are you staying in the historic core? My general-purpose guess in these situations is that you'll neither save much nor lose much by buying a pass. I don't usually buy them, which has worked right for me, but I use much less public transit than the average tourist.

Watch out for ATMs that try to sucker you into conducting the transaction in dollars so they can use an exchange rate that greatly benefits the ATM owner. That is common in Prague, and you may also encounter the same problem when paying by credit card. Stick to korunas. You may also encounter ATMs that charge fees; that practice is spreading rapidly.

I was in Prague in December for 3 nights. I ended up walking everywhere as the weather was beautiful so I cannot comment on the transit pass.

The water is perfectly drinkable to no worries there.

My hotel had an amazing breakfast that filled me up until dinner with a small snack in early afternoon. I went to the supermarket and picked up chips, fruit, bars etc for snacks and hotel room. I ate at smaller places but also ate at Christmas markets which were maybe a little more. I still spent very little on food. ( maybe $25 a day) I did eat at lokal one night and would recommend it. I also am not an alcohol drinker and found that the soda sizes were a little smaller than what we would be used to here in North America but unlike the US, they also do not fill up all the space with ice ;)

I mainly used my credit card for payment. I had brought over $100 CDN worth of Koruna and never had to a visit a ATM and came home with some cash left over.

Hope this helps a little

Normally I would buy the multi day pass, but now I am wondering. What would you suggest?

On my first visit to Prague I had a transit pass, and loved having it. On my second visit, I did not, and didn't need it.

On my first visit, when I had the transit pass, it was included with the Prague Card. (That is no longer the case.) Even with the pass, I walked over 14 miles one day. I took a tram to get up to Castle Hill and walked back down into Old Town. I used trams to sightsee up and down the river, hopping on and off wherever I felt like. I was covering a lot of ground and used the trams to cover the distances and make best use of my time.

I liked having the pass because then I didn't have to think about it or decide each time. I could do whatever made sense at that moment. As it turns out, I used the pass more than enough to justify it.

On my second visit, I wasn't trying to cover as much ground. My sightseeing was more focused in a smaller area. I walked nearly everywhere, taking the metro just twice - one of which was to the train station on departure day.

So there's no single answer - even for an individual! At 310 CZK (approx. $13.65) you can do the math to compare buying the 72 hour pass vs 30 minute or 90 minute tickets. Or pick one day and get a 24 hour pass.

will try to do my evening meals at Lokal or something akin to it).

When I was in Prague in early October (2019) I couldn't get in to Lokal without a reservation or a 2 hour wait.

I plan on downloading the Google Map for Prague about a week before arriving. Is this going to work when I need it ( I have back up hard copy maps

Downloading Google Maps for offline use will give you an excellent map rather than the hard copy. Offline maps do not include walking directions or real-time transit. You can see what you'll get by downloading the offline map for your own neighborhood and turning off your data.

I am regular traveller to Prague and have been for over 25 year , I will be in the city again next week.
Transport tickets Validate once and Once only ,m otherwise it is invalidated and you can get a 800kc fine.
Once stamped they last for the time of the ticket,30minutes,90 minutes, 24 hrs or 72 hours depending which ticket you buy.
1. depending how much you are going to use the transport sytsem several 30 minute and 90 minute tickets will work fine, 24hr tickets are great just for the convienence factor.
2, google maps are great and I use them often when in the city, even someone like myself that knows prague pretty well still can get lost.However don't rely on Google maps for transport links they are often out of date.
3.tap water is fine never had a problem drinking it.most Sodas are in 500ml bottle but 1 litre and 2 litre bottles are available. 330ml cans are also available.
4. 800-1000kc per day per person will allow you to eat and drink well,3-400 kc should let you have a main course meal and a couple of drinks in places like Lokal, soda is more expensive than beer.

Hope this helps

Try Kofola, the local soda,slightly aniseed flavour but they also do peach and blackberry flavours.Some restaurants and bars even have it on draught

yes to kofola! As a non alcohol drinker, it was nice to try a local drink that was not beer!