In regards to the headlights did you get a response from Lexus?
I am thinking of visiting the Lexus garage in la Roche sur Yon and asking at the service desk. It's probably quite rare that the question is asked and I'm sure they will prefer quoting for new lights. Knowing how things seem to work here in France, especially when a bottle of Ricard is envolved, who you know makes more difference than what you know. That could be why some people seem to get a CT paper and others not. I'm sure some French mechanics see the English plates and fail the lights without even testing them.
I would guess any garage with a headlight testing machine will be able to tell if the headlights will pass or not. I remember the chap in the garage tried to adjust my Zafira headlights before he changed them. He showed me the machine and I watched while he made adjustments, this is why I am hopeful that flat beams will pass.
If you do manage to get sorted with your mot document you will still need to pass a CT when the mot expires, maybe even before for the French insurance.