VPS configuration & setup for multiple Joomla sites

I have developed a Joomla-based web portal add-on for company web sites. I want to move from my shared hosting development server to a WHM cPanel/Virtuosso VPS environment. I need assistance in configuration and setup of the VPS to accomodate multiple Joomla client sites optimized for speed, performance and accuracy. I have sufficient experience with regular cPanel operation, but I am new to the server environment of WHM and Virtuozzo. Here is a breakdown of the intended setup: 1. I own 3 domain names that I have pointed and trasferred to the the VPS host: a) [login to view URL] - this the main product web site, which serves marketing, sales, and demos b) [login to view URL] - this is the production website that will contain all client sites c) [login to view URL] - this is the main company website that own the product 2. I have ordered 3 IPs from the VPS host. Each of the domains should be pointed to one these IPs respectively. The VPS is running WHM 11.30.5 (build 6) on CENTOS 5.7. When I transferred my first Joomla test site, the site wasn't running correctly (some components didn't display properly, etc.) I have used EasyApache to rebuild the server and everything works now. I had to downgrade from PHP 5.3.9 to 5.2.9 and enable a few mods. In this process I had to realize that there are just way too many settings that I am not familiar with. Therefore my quest to get some help in fine-tuning the settings and configuation I need help with setting up is the following: As explained before, the Joomla sites I build are add-on portals hosted on my VPS that extend the scope of existing company web sites. Scenario: I build a portal for CLIENT01 that will be hosted on CLIENT01.MyProductName.net. CLIENT01 owns company website [login to view URL] and wants to be able to access the portal by going to PORTAL.COMPANY01.COM. Rather than creating a cName record on [login to view URL] that simply points to [login to view URL], I would prefer to give the client the option to create an A-Name record on [login to view URL] that points to my IP ([login to view URL]). I would like to know if and how it is possible to set up my VPS server, so that when requests from [login to view URL] are made that traffic is directed to the corresponding folder. I hope I was able to convey what I am trying to achieve..... I would also like to get your advise on whether to set up new client sites as new ACCOUNTS on their own subdomain with their own respective cPanel or to simply create subdomains through a single cPanel instance for all clients. The portals are build in a way that the client would never need to have access to the cPanel (not even to the Joomla Admin Panel in most cases). What are the implication to the scenario above? How do multiple cPanels vs. one impact server load and disk space? How is sendmail function for Joomla effected? etc. I am looking for someone who can assist me with this configuration in one or multiple screen share sessions through [login to view URL], since I am not willing to give out my server credentials and would like to be part of the configuration process. I can communicate via Skype, email, FaceTime, GV+chat, phone....etc. I am not only looking for help with this initial configuration, but a partner for future projects and Joomla related questions.