Does Canadian GC holder need US visa?

[AmericanPie]

I have applied for Canadian GC. Once I land in Canada, do I need a visitor visa to visit the U.S.?

[immihelp]

no

[deymayor]

How long can they stay in the US?

My parents will be Canadian PR inext month. I'd like for them to stay with me in NJ for the majority of the year. How long can they stay continouosly in the US? And can I file for them to get a US greencard as soon as I get my citizenship (I'm currently a greencard holder)