Re: Billing - Telco, Cloud, Services
It should be possible with a few hacks and tweaks. I would create some script that is able to import the CSV or read the data and then import it into WHMCS database for billing.
It can't do this out of the box but I would advise you to look into the API and hooks for extending it. (more into the API), I was able to make WHMCS (in the past) bill for usage that was not calculated or done by WHMCS at all. Basically I just used the API to bill the customers and create the invoices manually based on the data (external) that I read on the usage. It required several PHP codes and with crons to run things.
So yes, I think it should be possible. Telco, Cloud, etc, are services in the end and WHMCS is designed for billing services in general. Look this for example:
This is used by ISP's to bill for Internet access.
WHMCS is a good fit for the services you mentioned.
An ash I know there stands, a tall tree, connecting the nine worlds. Yggdrasill is its name.