1) When answering “Amen yehei shemeih etc.”, one should make a short break between the word “Amen” and the words “Yehei shemeih etc.”, as the Amen is responding to the cantor, whereas the “Yehei shemeih etc.” is a separate statement whose translation is “His great Name should be blessed for ever and ever. (Shulchan Aruch 56)
2) One should not stop in the middle of saying “Yehei shemeih etc.”, but it does not need to be said in one breath. (ibid)
