Both of these can be polite, but it all depends on the tone of your voice you use. If you you speak with a calm tone of voice and a smile, they are polite. If your tone of voice and your face are very serious, a person could be offended. English has many subtleties and we can say the same words in slightly different tones and transmit completely different meanings. If you are sending this message through a chat program, I would add 🙂 in case you are worried, or, send a voice recording so he can hear your kind tone of voice.

Like with most things, tone matters! Both are polite forms to get clarity but if you say either in a sassy or exasperated voice instantly not polite anymore. Say calmly and confidently 👍🏾.

in an informal setting, it is ok.

Not at all.

I think replying by "do you mean...." To confirm something