Q: Z と z はどう違いますか?
A: Z is capitalized and z is not capitalized. Letters are capitalized at the beginning of a sentence, the first letter of the name of a person or place, and all other letters are not capitalized.


Q: Z którego miejsca odlatuje samolot do Wietnamu? は 英語 (アメリカ) で何と言いますか?
A: “In which area does the plane to Vietnam take off?”
Q: Z kąd to zwątpienie? は 英語 (アメリカ) で何と言いますか?
A: Why you doubt? / Why would you doubt?
Q: "Z" Can you tell me how to pronunce "z"? は 英語 (イギリス) で何と言いますか?
A: The letter or the sound it makes?
Q: Z góry dziękuję za odpowiedź は 英語 (イギリス) で何と言いますか?
A: Thank you in advance for your answer
Q: Z は 英語 (アメリカ) で何と言いますか?
A: Zee in English (us)
Zead in English (Canada)

so ず would be romanized zu so take the first part off that sound before the u and add a e like in eat at the end

Zee (sorry not the best explanation of the sound).


Q: Z

How do you pronounce Alphabet “z”?の発音を音声で教えてください。
A: ”ずい”
Q: Z [ /zed/ or /zi/? ] の発音を音声で教えてください。
A: In America, zi.

Anywhere else, it seems like "zed". At least that is the impression I get from what I have read.
Q: I have taken over Mr. Z to become your company’s sales representative in Italy.

I work in Japan. I am in charge of an Italian subsidiary of a Japanese company. I email to the Italian company for self introduction. この表現は自然ですか?
A: Here's a business formal version for your future reference:

Dear [Company B's Employee]

I am writing to introduce myself to you and your team. I am [Your Name] from Company A. I will be Mr. Z's replacement  as the sales representative for your company and will be managing this account. (Note that Company C has a different account manager.)

I work out of Japan, but hope that we will be able to meet in-person one day.

Looking forward to working with you. Thank you very much.

[Your Name]
Q: I Z Q U I E R D O この表現は自然ですか?
A: Yes it sounds natural, but in America we pronounce Z as zee instead of zed
Q: I want to catch some Z. この表現は自然ですか?
A: It sounds mostly natural, but you would want to put "Z's"to sound natural such as "I want to catch some Z's."