thanks for your interest in the ISPConfig hosting controlpanel.
I've tried to answer your questions as good as possible:
1) Within ISPConfig you are able to assign websites to the admin, resellers and clients as well. Of course you need to create the Reseller and clients first.
The admin contains also all privileges of the reseller and their clients.
The reseller contains all privileges of its clients.
2) Within ISPConfig it is not possible to create users under a client.
Within ISPConfig, you need to add a client to the system, after that, you need to create the clients website, where you need to add the users of that site.
ISPConfig rewrites the vhost file everytime a modification has been made. For this reason, you should never edit the vhost file manually.
Within ISPConfig and for every website, there is a Apache directive field available, where you can add the directives for Apache2.
3) The default html folder that ISPConfig uses is /var/www.
Within this folder the webspaces are created like web1, web2 and so on.
Each web has a symbolic link to another folder. The name of that folder represents the fqdn.
For example: If you've created your first website within ISPConfig for www.mydomain.com
, within the /var/www folder you will find two new folders, like:
and web1 as well.
Each web, lets say web1, contains the user folders, the log folder, a cgi-bin folder and a separate web folder for the site itself.
You can not change this structure for every single website via ISPConfig.
4) You can not store websites within a client folder as you suggest. All the websites are stored within /var/www.
When you provide your client a login account for the ISPConfig controlpanel, every client is able to manage its websites via that single login account.
5) Within ISPConfig, you have an IP-list available. By default the IP-address of your server is stored here.
If you have more then one IP-address available, you can add those IP-addresses within the IP-list.
On the moment you create a website, you can choose the IP-address for that website from the IP-list, which means that different websites can have different IP-addresses.
You are always able to change the IP-address afterwards.
6) Within ISPConfig, you can define a webprefix. The default prefix is: "web[WEBID]_". You can change that prefix in whatever you want or you can even leave it blank.
You have to realise that this is a global setting and you are not able to define a different prefix for every single client.