Got Visitor 10 yrs multiple entry visa, but have questions about Port of Entry at US

[pvn]

Hello,

My parents got their Visitor B2 visa (multiple Entry 10 yrs) in June 2006, when I was on my H1B visa in the US. However, they did not visit me immediately after getting the Visa since my grandmother wasn't keeping well. I then permanently relocated to India (voluntarily) at the end of 2006.

Now my cousin brother (mother's nephew), who is on a valid H1B visa in US, is asking them to come to US for a month or two to visit him and for tourism purpose. My questions are as follows -

1) Are my parent's visas valid now? Will they have any trouble at the Port of entry?
2) Their nephew has already sent them an invitation letter along with his Visa, Passport copies and employment letter. My parents will be carrying these documents. Since they are self-sponsoring their trip, will they have to carry any bank documents? Are there any other documents that they need to carry?
3) Any other question that they might be asked at the port of entry?

Thanks,
Partha

[PraetorianXI]

1) Are my parent's visas valid now? Will they have any trouble at the Port of entry? They are still valid while they have not expired.
2) Their nephew has already sent them an invitation letter along with his Visa, Passport copies and employment letter. My parents will be carrying these documents. Since they are self-sponsoring their trip, will they have to carry any bank documents? Are there any other documents that they need to carry? They do not need all of those documents. The invitation letter will do.
3) Any other question that they might be asked at the port of entry? Questions regarding the purpose of their trip. This trip should not be longer than 5 months.