Hosts file and port mapping for web servers

Got a little web server going on.  But, I don't want to open up port 80 on my firewall for various security reasons, of course.

I have an secondary port, let's call it port 9000 (which it ISN'T so don't even try.)   .... (I said stop it!)  Router takes that 9000 and points it to a protected server. Said server redirects that port 9000 to port 80 and sends it off to the webserver.

It works like a charm, actually. Except for one thing (I guess it isn't so much a charm as a twig snapped in half): How do I configure a remote system to automatically request port 9000?

The windows hosts file doesn't allow ports to be mapped, only urls.  This can be solved with 'relative' linking in my html/php code, but I don't want to reprogram it all (which isn't that much I guess).

Is there a way to map ports much like a hosts file so that typing in: http://webserver will forward to a certain IP AND port?

Why not config the webserver to run on port #### and point the firewall to that ?

Also, opening port 80 and letting it point to your webserver does not present a greater security risk than opening any port and pointing it to your webserver.

The actual security risk lies within the webserver software, if it is secure, you are secure, if it is compromised only the user that it runs on is compromised, the rest of the system is still secure (except if you run windows, but then you wouldnt be talking about security at all anyway..)