I have tentatively talked a friend of mine, with lots of spare bandwidth,
into serving my low-to-medium-traffic web site from his IP as well.

Now, he is a MS kind of person (Windows, IIS) and I am a non-MS one
(FreeBSD, Linux, Java, . . .) He is also more of a hardware person than I

He does not want to affect his own IIS server and network or spend much
time administering it or dealing with it, so I promised him to minimize it
to nearly no time whatsoever.

He told me he would do it if at the minimum problem he could simply
"unplug my sh*t" :-)

SO I was thinking about having some king of hardware based switch/router
simply sniffing all incoming packets on port 80 (probably 443 in the future
for users login only no user's compromising data, he told me) and if they
look like coming my server's way directed to me, otherwise to his network.

Also he should also be able to simply take the router off the loop and my
network down and reconnected the way it was before with 0 configuration hassle

So, which piece of hardware would I need?

What kind of configuration settings are needed in my own ISP's DNS server?

Do you know of any other issues or zero-admin approaches to administering
a simple server?