Use one bridge and on the router all subnets are vlans, bridge does nothing but bridging ( no IP addresses, no dhcp etc. )
Follow this for VLANs - http://forum.mikrotik.com/t/using-routeros-to-vlan-your-network/126489/1
Follow this for AP/Switch - https://forum.mikrotik.com/viewtopic.php?t=182276
Follow this for Firewall rules - https://forum.mikrotik.com/viewtopic.php?t=180838