>50+ vlan IDs on one OPT interface.

Not sure.  I have 15 running right now with no problems.

>The monowall should give all clients on all VLANs a DCHP adress from one
>pool but keep the seperation between the VLANs.

You will have to configure the DHCP server individually on each VLAN.

>Also the OPT will be bridged with WAN with filtering and bandwidth
>management enabled.

My hardware does not allow me to bridge a VLAN with the WAN.  If I bridge 
OPT with the WAN my VLANs that use OPT as a parent do not work.  I am using 
Realtek onboard NICs.

This is just my experience so far.


Aaron