When using the Billable website creation, there are additional plugins available to help you processing the ordering, payments, ....
Such king of process is illustrated in the tuorial video 14, 14b, ..
www.jms2win.com/en/tutorial#jms13x-14b
The workflow that we proposed it the following.
One the JMS site is created from the front-end, it remains in the "pending" status and a plugin can be called to create a bridge with an eCommerce application to process the order and the payment.
When this eCommerce extension confirm the order, an update of the JMS site ID is performed to confirm the website and allows him to become live.
For the 1-jan-2015 and the new European Tax law that require to compute the tax based on the customer localisation, we recommend using the "Bridge for Hikashop".
We also have developed, in partnership with hikashop, a new "HikaInvoices" extension that you can find at
www.hikainvoices.com.
This extension adds the functionalities required in HikaShop to process the "MOSS" rules and help in the tax reporting.
www.jms2win.com/en/joomla-multisite?page...70&category_id=1
So in terms of order and payment, you have the additional extension
- bridge for hikashop
- HikaInvoices for the tax reporting in europe.
Concerning the possiblity to automatically recognize the domain or subdomain, the solution that we currently using is the setup of apache to autoamtically recognize subdomain.
In general, we are using cPanel/WHM to do setup of apache with automatic subdomain recognition.
We don't know the procedure for debian.
What you need to do is probably to recompile apache to add the "vhost" extension.
With the apache vhost module, additional apache command will be availabel and will help you defining automatic rules for the subdomain recognition.