So tipping in Mexico… ELI5?

Hey there! My fiancé and I will be heading to Mexico this July for our honeymoon.

Coming from the UK, we're a bit uncertain about how tipping works at all inclusive resorts?

Our hotel (Unico 20 87) states that tips are not required but everything we're hearing online is that they absolutely are if you're a decent person and/or want good service.

We're very happy to tip if that's the norm but just have no idea how much to do so or for whom?

Another thing that's puzzling us is – assuming tipping is expected – where are you meant to get small notes for that purpose? Generally when you exchange cash here you're not going to get anything smaller than 10 bucks which I'm assuming (hoping?) will be a bit too generous? Can you ask the concierge to break bigger notes?

And finally! Is there a preference for USD or pesos?

Two clueless brits will very much appreciate any pointers!