2) Either buy a maple leaf lounge membership (likely hundreds of $) or priority pass (also hundreds of $). I'm not sure if MLL has day pass options.

3) Borrowing someone else's gold card to use is a bad idea. If they compare name on card with name on boarding pass you could find your friend's account gets terminated (and you'd be denied use of the lounge). However if another traveller (or FTer) was flying the same time & date as you and able to bring in guests (eg flying in F on *A or a *G member) then you might be able to be guested in.