First, here are some technical tips:
Look up the commands mv and cp on linux. Get familiar with their syntax. You can do this looking at the man pages on the internet, or by typing man mv and man cp on the linux console. Or you could login to the linux box and simply type cp --h or mv --h. Then look up the file functions for PHP. If you're moving files around on the same server, you don't need FTP... you just need local disk access. Next, look at the system() and exec() commands in PHP. You may also look at chgrp and chown and chmod linux commands-- I believe these all have PHP counterparts, and so does cp.
Your project sounds like what I like to think of as a "meta-site", it may be a meta-community-site but you didn't give those kind of details. Are you sure you actually need to recreate those files? Are you sure you can't dynamically generate those files based on database contents? At most, you need to generate possibly an index.php, but other than that, I don't see why you would need to generate any more files. You can do some pretty tricky stuff, and make it seem like the files are there, even though they are not. For instance, did you know you can use the extra path info as variables? Like maybe this is your site:
www.mysite.com, and your user bob as a site cityslickers. You can create a script named sites.php in your document root that uses extra path info to generate the needed pages. So, therefore www.mysite.com/sites.php/citslickers could generate his site. Moreover, using .htaccess, you can lose the extension and have apache process the extensionless file as PHP. So now you have www.mysite.com/sites/cityslickers. Now you can register www.cityslickers.com to point directly at www.mysite.com/sites/cityslickers... you could even fake www.mysite.com/sites/cityslickers/index.php, and the only file being processed by the server is the original sites.php. The index.php doesn't even exist, although it appears like it. so therefore, www.mysite.com/sites/cityslickers/aboutus.php could be typed in by the user, even though aboutus.php doesn't even exist... but it SEEMS like it. Everything can be stored in the DB.
Also, you may consider using another language that runs purely as shell scripts. PHP can be run as shell scripts.
Secondly, how come you don't have root access? Is it not your server? Are you yourself paying for access to the server. You may want to check your contract and make sure re-selling the space is within your rights!
Thirdly, I strongly believe that once you charge money for a service, you act professionaly about it. This includes being responsbible for what you claim you know, or the services you claim to offer. If you are getting paid to do something, I think it's even unethical to come here and ask how to do it. Especially since what you are asking is fully documented. Professionals do research, know where to look for credible information, and in general figure things out or legitemately outsource. When you come here looking for answers, you are asking us to give you work that you will be paid for. Do you honestly think that is fair?
Go ahead and spend some time with the manuals... another idea will always come, you will never be indefinitely stuck.
I wish you speed in your development.
PS just because you build it doesn't mean they'll flock to it and pay to use it... good business practice trumps innovation: look at the transcontinental railroad.