Kazakhstan seems to have become a fairly non-cash society - everyone is paying with their phones (using Kaspi). This has made the small change situation even more difficult than what is suggested by https://caravanistan.com/kazakhstan/money/. Often, shops won't have any small change even for a 1000 or 2000 tenge bill. That's true even for fairly busy supermarkets! in one place, I ended up buying some chewing gum because that was the only way I could pay for what I really needed to buy. In another place, the cashier saw my handful of coins and almost begged me to let her exchange it for a banknote. I had about 750 tenge in coins - she took everything and gave me 1000 tenge for it, mentioning that I couldn't imagine how difficult it was for shops to get coins. So start collecting them...!
It is true that virtually nobody can (or is willing to) speak English. I met a total of two people during my journey across the country that had sufficient English to talk to me - apart from *some* reception staff at hotels (and a number of Russian refugees). I do speak some Russian, so this wasn't too much of a problem. It is my impression that you hear more Russian than Kazakh in most places; virtually everything is bilingual (Russian/Kazakh). Be prepared to use a translation app.
WiFi at hotels has been fairly miserable - from non-existent to barely passable. In one case, the download speed was OK, but upload was snail-like. So don't count on hotel WiFi if you want to do VoIP or the like. Getting a SIM-card (from KCell) was fairly painless; I paid 4000 tenge for 17GB of data. Speeds were good in all cities I visited; between cities, reception is often non-existent.
Kazakhstan and Uzbekistan require SIM-card users to register their phone (or rather: IMEI number) after 30 days. If you don't (which you wouldn't as a tourist), the same phone won't work on your next visit to the country. The solution to this (apart from using a SIM-card from one of the other Stans in roaming mode - which is actually quite costly) is to get an eSIM that works locally in roaming mode. I'm in Uzbekistan right now and managed to set up an eSIM with 1GB of data for 4US$ (valid for 7 days). Just google and you will find...
When you are travelling on the new Talgo trains, internet reception is severely impacted by the thin layer of metal coating on the glass; the train seems to lack the typical equipment to pass through the signal as found in other modern trains (e.g. Siemens trains). The only windows without coating are the ones at the doors - and this is where reception is best.
Kazakhstan has two time zones. When travelling on trains across these zones, websites/schedules may not represent this in their information. There's a railway administration time and a local time. And some international trains may throw "Moscow time" into the game. So it's worth double-checking when your train is leaving and when it is actually arriving. Oh - and several of my trains actually left a few minutes early....
Public transport in Astana is easy to use - efficient and frequent. There is an app that also works in English (I think it's called "Astra bus") and you can buy a card with 10 rides at machines across the city (which also work in English). Public transport in Almaty is slightly more challenging. There's a smart card (Onay) that can be bought at many places, but you need to top it up at a machine. A friendly security guy helped me at the railway station. Once you know how it works, it is easy...

Yandex taxi is apparently no longer available in the app stores of many western countries - after all, it is a Russian company. I've heard there is a way to install it on Android anyway - I recommend setting it up before leaving your home country. Yandex will make your life much easier - no haggling with the taxi mafia at railway stations/airports, no language barriers. If you are an iPhone user, an alternative might be inDriver. I was told this was the best local equivalent, but since I had Yandex on my phone from last year, I can't speak from experience.
If you are into finding Soviet mosaics and the like (as I am...), there's an excellent page that will help you in Almaty: http://www.walkingalmaty.com/ There's also a Google map with the exact locations of lots of hidden gems set up by the same guy: https://www.google.com/maps/ms?msa=0&ms ... urce=embed
Crossing borders on trains is a nuisance. It'll take 3 hours of your life, and while there isn't really anything to worry about, it's not a pleasant experience (particularly for someone who is used to no borders in Europe). It very much reminded me of border crossings between and into satellite countries of the Soviet Union back in the eighties. You have to stay put on your seat - and no, the toilet definitely can't be used (even on modern trains where this would in theory be possible), so it's a good idea to plan your liquid intake/offload around borders wisely...

There are currently virtually no tourists in Kazakhstan. In more than 2 weeks, I met exactly one couple (from Poland/Israel) that was travelling the country. The situation is completely different in Uzbekistan.
OK - if anything else comes to my mind, I might add it at a later stage. Happy and safe travels!
Sebastian