Cathay Pacific Asia Miles - Which flight to LAX has the most mileage upgrade chances?

Now that CX is launching its third daily flight in LAX, I wanted to know that which of these three flights to and from LAX should I book so that I have the highest chance to upgrade my flight from Economy to Business using miles?

As a reminder: flights to LA includes 880(11pm)/882(4pm)/884(1pm)
flights to HK includes 881(2am)/883(12am)/885(1pm)

My next question would be if my waitlist for the upgrade didn't clear at the LAX-HKG sector, can I use miles to upgrade at the airport? (I know for sure you can't do this at JFK because BA handles the ground services for CX). If not, is there a set discounted price to upgrade from Y to J at the airport? (I know that it costs US$1500 from JFK-HKG and $750 from JFK-YVR)

Thanks so much

upgrade from y-c frm lax- hkg is $ 900.00 and C- f is $1,510

Now that CX is launching its third daily flight in LAX, I wanted to know that which of these three flights to and from LAX should I book so that I have the highest chance to upgrade my flight from Economy to Business using miles?

As a reminder: flights to LA includes 880(11pm)/882(4pm)/884(1pm)
flights to HK includes 881(2am)/883(12am)/885(1pm)

My next question would be if my waitlist for the upgrade didn't clear at the LAX-HKG sector, can I use miles to upgrade at the airport? (I know for sure you can't do this at JFK because BA handles the ground services for CX). If not, is there a set discounted price to upgrade from Y to J at the airport? (I know that it costs US$1500 from JFK-HKG and $750 from JFK-YVR)

Thanks so much

The price is $1200 last time I asked.