Your question can only be answered if we know where you're going. Some countries require visas from US citizens, others do not.
Probably a ten-year wait if at all.
Yes, an Indian citizen residing in the USA can apply for an Australia visitor visa.
he has to apply in the country of which he is a citizen: eg: a German citizen living in Denmark must apply at the German consolate to obtain a Visa
Yes, a return ticket is typically required for a US visitor visa to show that the visitor plans to leave the country before their visa expires.
The maximum stay allowed for a US visitor visa is typically 6 months.
No US citizen does. No legal resident does. Only non-resident aliens on student visa, tourist visa, or visitor visa need work permits.
Nobody can work in the visa on a visitor visa. Short duration courses like cookery class that will not add any credits to a course can be attended using a visitor visa. But working in the US, that will enable you to draw salary is not allowed on a visitor visa.
Does not matter if you are a US Green Card holder or not, when you have an Australian visitor visa, you can go there.
The maximum length of stay allowed for a US visitor visa is typically 6 months.
A visitor visa holder can typically stay in the US for up to 6 months per visit.
a) a visitor with a green card/visa,,, or b) an illegal alien,,,or c) a U.S. citizen,, in that order these days
The maximum duration of stay allowed for a US visitor visa holder is typically 6 months.