us green card holder getting canadian visa

[immisab]

what takes for the US green card holder to get canadian visa to work there

1) how long can US green card holder stay in canada ?
2) how US green card holder eligible to work in canada ? or does he need a permanent resident status/work visa to work in canada. if so what is the process of getting permanent resident or work visa in cananda
3) does having US green card help in anyway for getting faster canadian visa