Yes the equivalent of LMIA in the USA is LCA, the TN visa folks don't need an LCA.I don't think so, you only need a valid job offer and your passport at point of entry to get the TN visa.
Job market in Canada is so bad that there are people who legit move here to get the passport and work in the US.
And I'm not talking about just Asian people, many Europeans/British people do it too.
Edit: there's a list of occupations that are eligible for this visa and if yours isn't on the the list then tough luck.
I'm assuming your friends are in a non stem background?
However the TN visa is no as easy anymore, I have team members who tried many times (3 to 4) and the USA border agents who have to issue visa reject the applications a lo. My understanding rejections are a lot more common in technology areas, particularly for GTA folks who try to get it at Niagara. All cases I know are Asians so I don't know if it is racism of the USA immigration personnel