the box around the con is as stated for paddlock view.
you can alos turn on "friendly paddlock, and get a box around a friendly.
offline you can turn on the lead computing gunsight, and it will show you were to fire for the paddlocked plane. crosshairs for each gun, you can check convergences that way too.
shift 1 2 3 so on selects certain engines. shift E selects all again. using that function you can change the MAN or rpm for individual engines, or straight out shut doen a certain engine.
read this page and print it out:
http://www.hitechcreations.com/ahhelp/keycmds.html