Network Segmentation with Fortigate 300D

Hii ,

I have to configure new Fortigate Firewall and keep separate zones in our network with separate vlan for each zone.

DMZ - vlan 10 - 192.168.10.0/24

Secure Zone - vlan 20 - 192.168.20.0/24

Internal Zone - vlan 30 - 192.168.30.0/24

I have a layer 3 Cisco 3750 on which I have configured this vlans. I do not any server in each vlan to communicate with other vlan and so creating SVI on this switch will defeat my purpose. DMZ zone will be communicating with Secure zone since few data base will be in this zone and so on..

Can i create vlan on Fortigate unit and than create policy for each zone ? I want to control traffic for each zone and only allowed servers should communicate with other servers in other zones.

Can i use one vdom for routing and place other 3 vdoms  for each zone in transparent mode ?

Attaching a proposed network diagram for reference.