And there are still unbelieving Jews today!
Please read Isaiah 28:15-25 as the Lord makes it clear this "sign" had a limited time application and the rejection of this sign would end in judgment of the nation of Israel. That did occur and tongues did "cease of itself" because it served the purpose God ordained for it within the time frame God ordained for it.
Yes! it is one of the nine manifestations given to the body for the profint of the body!
You are still confusing "sign" gifts with service and servant gifts. The "sign" gifts are explicilty connected with the "sign" of an apostles in 2 Cor. 12:12 whereas the other service gifts are not. The apostolic office no longer exists today and can't possibly exist today for many clear Biblical reasons.
First, due to its qualifications (Acts 1:21-22).
Second, it is clearly identified as foundational in nature not durative (Eph. 2:20).
Third, Paul explicitly states he was the "last" of apostles (1 Cor. 15:8) and the term "last" translates the Greek term "eschatos" which is used three times in the same chapter to mean the last with none to follows. The "last" enemy is death (v. 26) and it is cast into the lake of fire at the conclusion of the Great White Judgement (Rev. 20:15).Jesus was the "last" Adam (v. 45) and there are none to follow him. The resurrection occurs at the "last" trump (v. 52) and there are no more to follow it (Rev. 11:15-18).
Fourth, not one single solitary self-proclaimed apostles after the first century has ever passed the Biblical tests of a prophet and the apostles were prophets as they spoke and wrote by inspiration.