Exporting of resources across customers

Hi, Obviously brilliant Azure community. 

I work in a company that is an Azure partner and we have maybe 80 customers with 4-6 servers each. We have the following needs:

1. See how many of the customer's Test servers are on right now
   1. This is due to us having some budget offerings where the customer only pays for e.g. 20 days annually for test.
2. See what servers types they have and how much storage is mounted
   1. This is to make sure they don't have more storage mounted than they pay for
3. See when reservations run out for those servers
   1. This is to make sure we renew them. They are currently not set to auto-renew. Also, it will show if we forgot to reserve a new customer.

To solve this need i thought i could like do a weekly export that i distribute in the org and actions are taken. 

For the life of me i cant find any resources on the internet helping me on the Customer level. its always for each customer and that will take a day for me with the speeds the portal has. 

I would appreciate some help and good advice. I cant be the only one with this problem.

Regards

Henrik