Replying to Ski size and boot flex for pow and trees?

Hi I'm 22 6', 160 pounds and I'm looking for a pair of powder skis that can let me play in the backcountry and trees. My question is what size would you recommend for me being the Armada Magic Js the skis I would like to buy unless you recommend something else for me.
I'm planning to stay four months in Vail this season and also have a doubt about which ski boot flex would be the best for this type of skiing.
Cheers,
Manu from Argentina