First, I do not own a Lyr, but I do have considerable experience with 6DJ8 tubes in another amp...
Dampers are not mandatory. However, wait until your tubes come in and then decide. If one or more is a bit microphonic, a damper just might help. That said, I have never used them.
Again, since I do not have a Lyr, I do not know for sure if there is enough clearance to accommodate dampers, but I suspect there is. However, a socket saver will make rolling tubes much easier, that is extracting and inserting, and they are quite popular in this forum. But again, I suggest you wait until you your tubes arrive and you have swapped them in and out a few times, and then make your decision.
Thanks a lot for your reply, By microphonics, shall I understand vibrations? Sorry, I am new with tubes!