Does & Is

[ofd]

Dear all,
Why we used Does in the first question and Is in the second?
Thanking you.
My cousin lives next door to Brad Pitt.
Does he? Wow!
My grandfather’s learning Italian.
Is he?

[mara_ce]

These are question tags. Your examples (a positive tag following a positive statement) are less common, but they are used to express interest or ask for confirmation.
So you like working here, do you?

In general to form a question tag we use:
*the correct auxiliary verb, e.g. do/does for the present, will/won’t for the future, etc.
*a pronoun, e.g. he, it, they, etc.
*a negative tag if the sentence is positive, and a positive tag if the sentence is negative.

Question tags are often used to check something you already know is true.
Your name’s Maria, isn’t it?
You aren’t happy, are you?
The match finishes at 8.00, doesn’t it?
They don’t smoke, do they?
She worked in a bank, didn’t she?
He didn’t like the film, did he?
We've met before, haven’t we?
She hasn’t been to Rome, has she?
You’ll be OK, won’t you?
You won’t tell anyone, will you?

If the intonation of the tag rises, it may be a genuine question, or a request for information.
If the intonation of the tag falls, the speaker expects agreement.

Hope that helps.