We start here as base:
http://forum.mikrotik.com/t/using-routeros-to-vlan-your-network/126489/1
Any reason why you do not have VLAN30 interface connected to bridge ?
/interface vlan add interface=bridge name=VLAN30 vlan-id=30
You need one vlan interface as slave to bridge for each vlan you want to use.
Each vlan interface gets its own IP address with the subnet appropriate for that vlan.
The DHCP server should then be connected to that interface, not bridge.
So 4 DHCP servers, each connected to their respective vlan interface.
The best you can do is to download the appropriate config which is presented in the thread I linked to.
The config to be applied is really STEP BY STEP explained in those configs on what you need to do.