Does Apple Pay and Google Pay work anywhere I see the tap symbol (looks like a rotated wifi symbol)? Or they must also display the Apple or Google Pay symbol? I've seen places that just have the tap symbol and wondered if I could've used my phone.
Yes Apple pay and Google pay do work with all contactless payment terminals, however your card may not. If the business does not accept Amex for example, using Apple Pay or Google Pay will not work unless you pick a different card.
Generally, yes, at least in the US. There are exceptions; some chains have decided not to support Apple Pay, for example. But the contactless symbol generally means any kind of contactless payment system is accepted, including Apple Pay.