Some questions about cargo routes (ATO2)

I have some questions regarding cargo routes for airtycoon online 2:

• How much does plane age affect profit for cargo routes? I have a fair few cargo routes, almost all of them are monopoly routes, but all the planes on them have been run down for a while, and now their airplane satisfaction ratings are half that of a new variant of the same plane, how will this affect profit? Will less cargo fly on my airline because of the old planes, even for routs that I have a monopoly on?
• How does satisfaction work for cargo routes? There are no passengers on cargo planes, so I would think that the satisfaction of the route would matter less than on passenger routes. What influences satisfaction on cargo routes, how much does it influence it, and how much does satisfaction as a whole matter?