I plan to purchase a ticket from US to England on kayak, then use my AAdvantage points to upgrade that ticket to business class. I have questions:
1) Is this even possible to begin with?
2) I saw another thread that talked about a flight purchased on kayak that used codeshare - how can I avoid that to avoid the headache that comes with it?
3) American Airlines' site has a chart that says "Discount Economy" tickets require 25,000 miles PLUS $250 to upgrade - per ticket! While the "Full-Fare Economy" tickets require only 15,000 miles. I assume my kayak ticket is considered "discount economy" - correct? So according to this chart will I have to pay $700 plus 50,000 miles to upgrade a $700-something ticket?!

Thanks for any guidance anyone can give me on this. I would really like to fly a redeye comfortably, using only miles to upgrade if possible.