Getting Sponsered / Job Offer Letter

Hello again all you immigration gurus!

Things are starting to come together but i need further clarification on a few points if you please.

1st scenario
I read somewhere that if my French National husband is flying to Canada and has a job offer letter at the point of entry they may issue him with a work permit. Can this be true, also can this happen whilst he has a spousal sponsership application in process?

2nd scenario
Also - If whilst in Canada, he gets a job offer and someone is willing to sponser him. How long does this process take
What if after some time he ceases to work w this employer, does he have to get a new work permit?

Help is once again GREATLY APPRECIATED!!!

oh..by the way he is a professional Sommelier, (a wine taster), which can be maybe a specialised role in the hospitality industry as there aren't much in Canada i believe.

thanks