choosing self-IPs for iQuery communication

Iquery should be on a different VLAN than your DNS traffic... Do you have a Firewall?--Adds another degree of security.

'bigip_add' is the IP in which your GTM and LTM's will communicate. If you want a different IP, then you will have to readd your LTM and/or GTM's, via bigip_add with a different IP.

Also your DNS Listener should be using a different IP than your Self IP's.