Hey cool. I have the same router and likely ISP hehe. I'm delighted to see other people are seriously planning to use the pi as a webserver. Its more than capable ..
Glad you mention free dns options.
Those sites are great and hugely useful if you want to host a webserver using a registered domain (ie .net .com) on residential broadband. Guys like plus.net actually let me have a static ip but other popular companies like virgin media don't. So you need to update your DNS A register manually whenever the WAN ip cycles (mercifully not very often). Using a free dns update script that are usually bundled by the free dns providers in crontab has allowed me to ssh in to my server with the new WAN IP from wherever I am at the time and then manually update the registered domains dns register from the shell there. Without such a service I would have to have physical access to the machine to update the dns. Saved me time and again .. and its free. Can't beat that
On my pi I used the bog standard current raspbian image, pruned all the guff out back to a basic headless box.
I kept it simple and installed sshd, lighttpd instead of apache (lighttpd is just easier and quicker to configure for 1-2 vhost sites imho) and mysql and php5. I've boosted things a bit performance wise by recompiling the kernel to remove all the fluff I don't need, installed xcache with a 32mb memory map for caching the php I'll soon be using on the site's main pages etc.
You can see my pi stats here: http://220.127.116.11/
I also have a domain hosted on the pi using vhosts on a different path but thats not setup fully yet, like your site is. So far tho I have stress tested over 60 unique ips as incoming connections (a figure quite realistic for someone's home server hosting a low traffic site, forum, mumble server, mysql databases etc) pulling image intensive pages etc. Each hit uses 35% of the pis cpu via php5-cgi which is a problem but the memory caching via xcache helps a lot with multiple concurrent requests, effectively neutralizing the overhead. All static pages and content ofc works totally fine, at least as well as on a machine several times the spec. There is obviously a small delay vending php or js intensive pages like the punbb forum, 2 seconds or so per call (mostly due to the compression), but its well within the realm of 'not annoying' for a home server that will, hopefully, save me a LOT of money on my electricity bill over coming years.
That said, one thing to note about 24/7 pi use is that the power consumption is actually pretty bad unless you are using a proper psu and/or switching wall plug adapter. Its worse than my atom 1.5ghz netbook which was the server until I got the pi. Hopefully a better quality switching psu to replace the linear phone charger I have made do with thus far will resolve this (one ordered). I notice you have a link to what looks like an ATX psu chop up? That surely will waste loads more electricity by virtue of being severely under loaded .. ?