You have to check the planes you own in the control panel and then remember to save that list.
As to mission length, there are two things to adjust in the Configuration menu (again on the opening control panel.)
Way down near the bottom you will see Max Offensive Mission Length. I set that to 30 (I think it's kilometers). Some people use even less.
If you use Air Starts (change the 0 to a 1) you can adjust the "Distance to objective" at the very bottom of the list. I like doing ground starts so don't use it but it's there if you choose to use it.
You can change the odds of running into enemy patrols (I haven't tinkered with that). But I try to play it realistically and if they have me outnumbered, I simply retreat without engaging them.
Again, remember to save or accept your changes before you close the panel.
My only real gripe with the PW camapign is the AI, which is a 777 problem, not something Pat did.
Criquet has made a modified AI mode that helps considerably improve the AI. You can find it here:Mod AI
You have to fly with Mods On.
Hope that helps.
Happy New Year!
HTExceptional engineering...and a large hammer to make it fit....