Yes, a J-1 visa holder in the US may bring their spouse and children under the age 21 under J-2 dependent visa. They must maintain their status in line with your J-1 status and complete the required application processes. Subject to specific restrictions, people can apply for work visas and study after they arrive.
No, A US Green Card holder can't marry a Filipino and bring them back to the US. The spouse will need to apply for a Visa to be admitted into the US.
Yes, she can apply for a visa to bring her spouse to US
If they are derivatives of the original petition- yes.
If you are a Canadian citizen and your spouse is a TN visa holder, you may be eligible to apply for a TD visa, which allows you to enter and stay in the US as a dependent of your spouse. However, the TD visa does not grant you authorization to work in the US. If you want to work in the US, you would need to separately apply for a work visa that suits your qualifications and employment situation, such as an H-1B visa or an L-1 visa.
Can a US green card holder marry a filipino and petition for a spousal visa to the US
That depends on whether the foreigner actually was actually a spouse, or just a holder of a spouse visa (green card).
Yes, a US passport holder needs a visa to travel to Australia.
NOT SURE.
No
Does not matter if you are a US Green Card holder or not, when you have an Australian visitor visa, you can go there.
A B1 visa holder can typically stay in the US for up to 6 months per visit.
A visitor visa holder can typically stay in the US for up to 6 months per visit.