I am new to the bidding for upgrade, and have a few questions.

1. If I already paid extra for premium economy(exit rows with more leg room), does that improve my chance compared to someone who bids the same from regular economy class?
2. How to determine a reasonable bid?
3. will I get a seat if I bid the highest?

I currently placed lowest bid available(US $860) for upgrade to Business class. I wonder what a reasonable bid should be? Will I get upgrade if I bid the highest in the $1500 range?

I would appreciate it if anyone can look up how many seats are available in business class.

AC28, 3/18/2022, Shanghai to Toronto