Aircraft Leasing/Ownership and Private Terminals

Hello all hope you are well - I ran into a few features I am unfamiliar with despite playing this game on/off for years now!

For Privately built terminals is there a way to see the exact capacity being used? Currently I add routes to my new terminal til I get the notification that it’s overbooked.

And more importantly! I ran into the Leasing tab and found out that I can purchase aircraft I’ve leased for free/very cheap in some instances. What triggers this? After a certain amount of weeks of paying the leasing installments you’re able to purchase the aircraft for free?

I am playing as Arabian Skies on the Yeager VIII game world if that matters

Cheers