Have much experience in setting up Cpanel/plesk and homebrewed "inhouse" web server configurations.. as well as open source solutions like ISPConfig
Experienced linux administrator for 5+ years..
currently administer many web servers for a california ISP
Depending on what route youd like to take.. you can choose to install an easy to maintain control panel such as Cpanel or plesk.. and makes it easier for your end users
or you can do a more hard to manage installation using just the tools built into linux.. either one i could setup for you...
First step ideally is finding out what YOU want to do as a provider... control panels? or manual hosting setups etc.
after that depending on that.. I'd custom build you a web server with the requirements you need.. apache .. php.. Mod_perl.. SSL ftp server...
secure the system tightly.. mod_security to prevent XSS (cross site scripting) and common bugs in popular software (phpbb/vbulletin and many php based CMS software)
secure the system level access.. firewalls.. determine your exact network needs and establish QoS settings for your server.. faster HTTP response in exchange for a slightly slower SMTP resonse
proccess prioritization... you dont want anti spam and/or backup tools eating up your CPU slowing down your site giving the hosting company a bad image.. proccess priotization can increase your servers performance about 20% over one that isnt.
perhaps you need virtual hosting... and so on.. shared hosting etc
It's really up to what kind of provider you hope to achieve being..
I can also show you integrated solutions using Cpanel + billing software to make your life easier on billing as well..
Anyhow.. this is my bid and hopefully we can achieve and come to an understanding together and work together to build you exactly what you need.
Thanks for your consideration.