depends how you do it
there are different ways to do the ot thing
if i were to say my sharks +ot vrs your jets... that means if my shars win in regulation or the game gets to ot, i win. you only win if the jets win in regulation
if i were to say my sharks vrs your jets.... that means who ever wins the game outright, wins the bet
you can also bet plus points (+0.5,+1.0,+1.5,+2.0,+2.5, ect) or minus points (-0.5,-1.0,-1.5,-2.0,-2.5, ect)
the .5 makes it so there would not be a push, while a whole number could result in a push
as far as how many bets, yes you can have as many as you like as long as you can cover your losses
if you have any more questions feel free to ask