VOIP Device under F5-BIG LTM

Dear All,

       Please advice all configuration in this infra,  My requirement is shown in Diagram.  I already added route in  F5 (route 

       1. Do I need Source Address Translation (AutoMAP) in f5 Virtual Server ? Listen on External Vlan
       2. Do I need Virtual server listen on Internal Vlan for 192.168.10.97/32.
       3. I am using multiple ISP load balancing, I want to out voip device to that ISP1 only, So do I need irules?