Carl Tyler's Blog

1 - No, that is not possible. DNS will resolve one IP adress and forward the request there. You can however create virtual hosts that take a http request and direct it to the appropriate directory. Or you can use different ports on your router and forward them to different hosts inside your own network.

2 - Beg to differe, my friend, Volker.

It depends on the product. Higher end firewalls can look deeper into the packet than the destination address, and can make decisions based on protocol level data (like the request server name in the http packet).

Of course, those firewalls tend to be more exensive than getting another static ip would be.

3 - This kind of functionality typically is handled by a reverse proxy. So one box needs to be hit first. There are probably firewalls that come with a reverse proxy module. So Andrew is right, however that is not considered a "core" firewall task, so Volker is right.
Apache has reverse proxy capabilities and you will find a lot of stuff when searching for reverse proxy or load balancing on Google.
Hth
stw

4 - Short answer for redirection of *all* ports: No, that's not possible with any current technology - at least not in the scenario I believe you want to set up.
Short answer for redirection of HTTP requests only: Yes, any reverse proxy / load balancer like Squid or Pound (http://www.apsis.ch/pound) will do.
Short answer for redirection of HTTPS requests: That depends on the product used. Pound has limited support for that.
If you're interested in a longer, more in-depth answer why it's not possible to redirect any other traffic than HTTP, let me know
-Stefan