Basic traffic group / floating IP question

Hi,

The floating and none floating address on the external interface are purely for the BIG-IP.
Use a different IP for the virtual server that in the same range as the external interfaces. This address moves at the same time as the floating address. But think as one for the system and one for your service.

Other than that it'll depend on what services are running and how you are desiging them.
So one vs/ IP per service/app per site.
Or one vs/per per site and you can manage other services by url and via a policy and use something like vip targetting vip to only present 1 IP per site.
If you pay per IP at your DC's then this can really help scalability.

Then you can simply use GTM to manage which site/service to be using and where.