Looking on flight star the Cazaux area is a maze of restricted layers from ground up to unlimited. In fact there is so much of it I'm hoping if on a FIS then going through it should be ok.
You need the SIA chart. Flitestar doesnt show this stuff clearly.
But the RAs off the west coast are real and go to high altitudes. A suitable route is slightly inland - I will send you a PM.
IO are those class E routes shown on the charts you put the link to.
Yes. For serious French VFR the 1:1M SIA charts are a must.