SCAC CODE....?

hello every one. i am a new privet carrier own a stepdeck trailer.today i had a load from canadian broker.he told me to pick up container from the port deliver to customer and bring empty back to the port,we aggreed on the rate and everything, i ask him for scac code, he give me 2 scac codes he is not sure witch one is good. so i went to the port at the gate they ask me for scac code i give them one he told me are you sure is right,i told him i have another one, he told me listen to me you can use any scac code you want. but if it's not right you will not get paid even you pick up container and deliver it.he scared me and aske him if i can use my scac code instead. he told me it's ur problem u can use any one you want.
i cancel the load and went back home, i didn't want to take chance to drive 1200 miles for free.
so my questions are
1, does every container has to have a scac code to get it released or what?
2, does the broker provide the port with scac code for that container to make sure no one get that container other than dispatched carrier.
3.let 's say broker give me wrong scac code, and did make delivery and return empty container back to the port,why i should not get paid .if it's broker mistake not mine
4, what i should do to use my scac code in the future,since i already had one . are there any fees or charges if i use my company scac code
5. do i need to let my insurance know that i have scac code
6,do i need to have scac code even iam not using theire chassis. i will be hauling just container on my stepdeck trailer
thx for help