I’m not sure, I heard from others that it needs to be cash.
I always carry cash. It’s not much, €500 each and you’re good. I’ve never ever been asked to show funds or accommodation or return ticket, but I always have it just in case.
It’s always better to have something you won’t need than to need something you don’t have…
as a Filipino citizen she gets 60 days visa exempt on arrival, she can then extend 30 days more. The same goes for you if your nationality is allowed visa exempt on arrival. 93 countries has this so I assume you’re of one of those nationalities?
Immigration usually don’t care about your return ticket, airlines do.
I always have a bus ticket from Thailand to Cambodia 250b booked with a date previous to my 60 days expire just in case someone asks.