VPN conc from CISCO has routing functionality. It has its own routing table, also it supports routing protocols like OSPF and RIP. In this case, the packets from web server will be routed to the firewall interface. In the VPN concentrator, you should specify the default gateway as the Firewall inside interface. The following link should help in configuring the default gateway.
I assume, that since you have vlan 1,2,3,4 in the inside network, you might be using a router for intervlan routing also. This could be either a layer 2 switch with a layer 3 external router or a layer 3 switch. If thats the case, you might want to set the default gateway as that router itself. If there is no router in between the VPN conc and the inside lan, you can set it to vpn concentrator inside ipaddress.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...