Hello,my name is Judith. Thank you for this opportunity to answer your questions.
how long must she wait before she can visit Russia?
After you marry her and file the paperwork it takes approximately 90-120 days for her to get her Advance Parole which allows her to travel.
Does it require a visa from Russia?
No because she is a Russian citizen and has a Russian passport.
She has to have the advance parole from the USCIS to be able to come back here.
I assume she can have dual-citizenship, yes?
She has to be a permanent resident first for at least 3 years before she can apply for US citizenship.
US allows dual citizenship. I do not know Russian law.
What is required of her to begin working in the US once she is my wife?
She files for her work permit and advance parole to travel when she files for her adjustment of status to become a permanent resident.
BTW, in regards XXXXX XXXXX prior question that you answered for me, a Russian friend told me a man got his Russian girlfriend into the US by booking her on a group tour to NYC and DC...which she did not even end up visiting.
Yes, many Russian women book tours as a way of coming to the US. It is fraud if they don't meet the tour group. If USCIS finds out she did not join the tour they can deny her the right to live here because of a lie.