Q2 : If traffic is initiated from server behind internal vlan , this server is not member of any pools , will it be routed according to F5 Routing table ( same as router ) or traffic will be dropped ?
As Hamish said, it doesn't matter if the host originating the connection is a member of a pool. Traffic will only be passed if the destination IP:port matches a virtual server or the client matches a SNAT. I much prefer using virtual servers over SNATs as you have more visibility and control using a virtual server.
If you do create wildcard address virtuals make sure to enable them only on the ingress VLAN(s) you want to allow clients from. Creating a 0.0.0.0:0 virtual server enabled on all VLANs will allow any client that can reach LTM to traverse LTM.
Aaron