I think it will definitely contribute. For example SpaceX also could learn from expensive mistakes like the Space Shuttle . I think it will be the same with ITER.
Yes. Don't put wings, flaps, rudder, and landing gear on a rocket.
Except SpaceX's Starship design does include moveable wings/flaps.
I'd call them fins, which are used to orient the rocket, not provide lift.
So a rudder?
Look at the size of the rudder on the space shuttle vs the size of the fins.
The lesson that was (or at least should have been) learned from the Space Shuttle was to not develop things that are obviously from the start bad ideas (as one of von Braun's Germans lamented "they reinvented the wheel, and made it square.")