DDNS:
http://www.EditDNS.net is another good dynamic DNS, it works with domains like abc.xyz
Where abc is the Second level domain and xyz is the top level domain.
Its free to use and alows control over the A, AAA, MX, NS, SRV, CNAME
More advanced features cost $6 for 6 months access to setup, but once set you don't need to pay after the 6 months unless you need to change a more advanced feature. I use the free service with my self hosted web sites and it works great.
Hosting:
The company I work with uses host rocket to host theirs and their customers sites on.
http://www.hostrocket.com/
They have 24/7 tech support (Actually called at 2am on Saturday)
Misc:
I haven't had much php or mySQL experience yet (I use SQL express and ASP.net 2.0), but would recomend making sure everything is up to date, and recheck all settings for any possible security holes.
I have two dual Xeon 2.6GHz HT (Device manager shows 4 CPUs) servers each with 1GB of Ram, striping Raid on Data Drives (SCSI LVD), 250GB SAN Storage for backups, VPN/Firewall router between servers and Internet
I used one of these servers to host the live web cast of PARC X.