Mezumin

I noticed in the Zmerios Yeshurin of Rabbi Hoffmeister that the leader of the mezumin before bentching does not repeat yehi Hashem mevurach... after the others at the table say it. I noticed also that the leader says baruch hu ubaruch shemo after he says Baruch Sh'alacahnu. The Hirsch siddur provides the same nusach.

I noticed also that the instruciton in the book says not to lift oneself up ('belo amidah') after saying elokeinu.

Is all of this standard Minhag Ashk. practice?