May I ...? - Yes, please

Not wrong but unusual. I would expect to hear extra emphasis in please.

Thanks a lot, AG.

Would "Do you want some? - Yes, please" be correct?

HUBLOTWould "Do you want some? - Yes, please" be correct?

Yes, that's the usual use for Yes, please.

Thank you, AG.

HUBLOTIs it correct to say "Is it all right for me to = May I"?

Yes.

Note that Yes, please do would not be a natural response to the questions in the last image. Yes, please do has a humble, obliging tone, and your examples suggest a parent-child relationship, so typical positive responses would be Yes or Yes, you may.

Thanks a lot, AG.

Janet: Is it all right for me to...?
John: Yes, it is.
How does this sound to you?

HUBLOTHow does this sound to you?

OK.

Thanks a lot, AG.