I need control plane security enabled and for the APs to re-join and get accepted by the controller for bridge forwarding correct? I will enable auto-cert provisioning so that any AP that contacts my controller will be accepted.
Correct
If I need to enable control plane security I should plan for downtime, correct? If so, any idea how long the whole process should take? Just one 3200 and 18 AP-105s in this
You should plan for a downtime for 30-45 minutes because APs need to reboot after you enabled CPSec, it may take less then that but just in case..