Bandwidth and Vnet relationship

Hi,

We are architecting a system on Azure and following is the architecture:

1. The system (on Azure) will access a web service on open internet. It will have the egress of 'X' GB.

2. The system (on Azure) would be accessed by some users (via Vnet). 

3. The system (on Azure) would perform sync with another system (on Azure but in a different region) via Vnet.

We have the queries pertaining to the costs incurred because of the bandwidth (data flow). Queries are as follows:

a. In the bandwidth calculation - would only the egress cost (mentioned in point 1. be considered)? Or will the data flowing over Vnet be also need to factor in (mentioned in point 2. and 3.)?

b. In the pricing calculator, there is an item by the name Inter Vnet transfers. According to my understanding - these charges would be applied to ne only if I have data flowing between two different Vnets. I wont be charged if the data is flowing in the same Vnet. Is my understanding correct?

c. Can I have same Vnet spanning across two regions?

d. If I have my system in one Azure region and a back up system in another Azure region and if both the systems are in the same Vnet, then do I need to set up the Site-to-Site VPN between my on premise and the Vnet only once? Or do I need to set it twice (one for every region).

e. Does setting up a Vnet incur costs - except for the VPN?

Request your help on this.


Regards, Saurabh