I’ve been in Singapore for a couple of days now, here’s what I’ve found so far -
Using the :mondo: card
- I’ve had no issues with card acceptance in stores. Stores do seem reluctant to try contactless payments using my card but every time I’ve used it, it’s been accepted.
- I’ve only used one ATM (OCBC’s) & wasn’t charged a withdrawal fee
- Uber is available in Singapore & just as cheap (2.9k trip, taking 15 minutes was S$7 or £3.96).
- I also used my card to purchase (discounted) tickets for the Gardens by the Bay online, via the Handy app (on a phone provided by my hotel) which went straight through.
When 
cash has been necessary
- As you’d expect, the semi-permanent street stalls don’t take cards though - I haven’t seen any signs of Stripe & their SG webpage seems to be for web payments only.
-
Buses don’t take cards, you can pay with cash but they won’t take $10 notes for a $2 journey & don’t give change.
The MRT has to be paid for using an MRT ticket, I paid for mine with cash & forgot to check whether card was an option.
The 
app
Transaction notification’s aren’t delivered immediately when on Wifi, I have to open the app and refresh the feed, in order to view them but I’ve found that this happens to my other apps too.
I have Travel Reports and I’ve found seeing the transaction amounts in £ & S$ has been really useful, when it comes to understanding how much I’ve spent.
As @dom mentioned, I didn’t see the ‘Welcome to Singapore’ feed item, with the current conversion rate etc. when I first connected to the internet, it appeared a few hours later after I made my transaction and not as a notification at that point.