Partially because they don't fully accept Zionism and consider themselves as diaspora Jews. The use of modern Hebrew is considered "too modern"/inappropriate for them.
Answer:
I live in Israel and have some relatives who use Yiddish as their first language. The reason is that it's a wall against assimilation into the non-religious.
Yes. Israelis speak English as a second language after Hebrew. In Mea Shearim, most people speak Yiddish and some speak English too. Some speak Hebrew, but many believe that Hebrew is a holy language that should be used in prayer and Torah-study only.
Yes. It's especially common in the Mea Shearim district of Jerusalem, the world's strictest, most Orthodox Jewish community in the world. The refuse to speak Hebrew, except during prayer, because they don't recognize Israel as a state, since the Messiah hasn't come.
The Yiddish word for Yiddish is "Yidish" (יידיש).
"Redstu Yiddish" is Yiddish for "Do you speak Yiddish?"
"Jewish" in Yiddish is "ייִדיש" (yidish), pronounced as "yiddish."
There is no equivalent Yiddish name for Robert. But you can spell Robert in Yiddish as ראָבערט
Yiddish is spelled as Y-I-D-D-I-S-H.
The Yiddish word for nosy is "shnorer."
The Yiddish word for disappointed is "Ahntoisht".
'Brother' in Yiddish is 'bruder'.
In Yiddish, husband is "man."
It is the Yiddish word for a woman who is not Jewish. It is slang in English, but it is not slang in Yiddish.