If you really want simplicity, stuff 3 model script for bash, plus the simplest webmerge exec'AUSA these scripts.
Example script: pastebin.com/eTwyAx23
(yuzaetsya on VPS'e, can be crooked)
Adding a FTP user with nologin, create a diry for a site, VHOST'a for Apache and user in MySQL. Works in CentOS. By analogy it is possible to write the same basic functions.