Can't really comment on running a webserver as I've never done it.
What I can say though is that my router/firewall is completely configurable. I.e. you can turn on/off security/firewall/IP NAT and you can add lists of ports that are allowed through the firewall. (It is one of the SAR703 routers from
www.solwise.co.uk).
You can add lists of addresses for forwarding also I think. Like I said, don't use this as gospel as I've never tried it.
As far as webserving/ftp is concerned though. I would say, if you can do it on a PC, you can do it on an Amiga.
Don't know if this helps. If you want me to try anything at home to test I will.