Back in college I had a professor who always used refferences from the reserve stack section of the library.
His reason for this was those books could not leave the floor that they were on and there was no photocopier, so we had to READ the material then make notes.
What brought this back to mind was your first photo.
Tractor Drive belt is just that it goes to the rear to drive the mower
And Blade Drive Belt well it moves the blades.
There should also be a decal on the deck or under the foot board to show you how the deck belt is routed.
Take the belts off and spin all the pulleys, if they make noise, replace them now before they fail and wreck your nice new expensive belts.