You will see the 11mm and 13mm on the drawings. It makes sense they would use the 11mm for the ailerons as the wing out there is thinner. 13mm would suit the wing thickness where the flaps go. You really have to study everything on the drawings, everything.

For example, they show a soldering iron touching the servo leads in two places. They're basically illustrating that you can't use the extensions as extensions, you'll need to splice in extra lengths of lead to get the servo lead through the wing.

They only show a couple of pictures and leave it up to you to realize what they're "saying".

About the 4 wing servos...........

They provide 2 left covers and 2 right covers.

Their drawings show the right wing from the underside, with the servos depicted, on a couple of pages. I never found a drawing showing the left wing, either from the bottom or top, that showed the servos. Both the aileron and flap servos in the right wing are mounted with servo arm, the top of the servo, toward the tip. Since their servo covers come with 2 lefts and 2 rights, then you have to assume they expect you to mount the left wing servos pointing away from the right wing servos. Otherwise, their covers won't fit over at least one servo. They expect you to mount the two flap servos in a way that will require plugging them individually, not through a Y. Are there other combinations that work? Beats me, I never thought about it much. I was going to mount my flap servos to utilize a Y and my aileron servos to also utilize a Y. So I knew I had one cover to rework.