Hello,
just a self reply to my post, for the community,
I found a way to address the first question (the names of the USB connection changing at each power-up of the host) in this post,
that is : Use the /dev/serial/by-id/… link and be prepared to restart the Addon several times manually until you succeed.
which is in the conf file of Deconz not to use the ttyUSB0 or ttyACM0 link, by the full name as displayed in supervisor/system/hardware.
It seems to works fine, for the conbee II and rflink usb gateways…
now, if anyone has info or solution for the zigbee item not pairing with the gateway when using the deconz add-on in HA, in spite they pair well when the gateway is on the PC and direct phoscon (not via HA)…
Sincerely,
V.