There are two questions here, one for MS clustering, and another one for Mongo.
MS Clustering
The decision of where to put the public, heart-beat, inter-node communication, and quorum drive is significant. Also cluster architecture makes a difference; you pick different quroum options if the two nodes are in adjacent racks than if they were in completely different datacenters.
Put the heartbeat on the same interface/subnet as the public interface
This theory holds that if you lose your public interface, you want the heartbeat to fail because this node is effectively down to users.
Put the heartbeat on it's own private interface/subnet
This theory holds that something outside of the cluster is arbiting who is doing what role, and unnecessary node-death is to be avoided.
Put the WFS on the heartbeat network
If the two nodes are in the same overall network (the same set of switches is supporting the non-public networks for both nodes) then putting the WFS on the heartbeat network doesn't introduce any new vulnerabilities.
If the two nodes are in different network fault domains (such as different datacenters), this is a bad idea. The heartbeat network provides the 'node majority' quorum option, and the WFS provides the 'File Share Majority' quorum option. You really want both options to be in separate fault domains.
Your revised diagram makes sense if both nodes are in the same data-center, though I myself would but the heartbeat on the public side.
MongoDB
MongoDB is a bit simpler. With even numbers of nodes, you absolutely want a third node to act as tie-breaker. They're pretty clear about that. However, your diagram states:
Up to 12 replica members (7 can vote).
7 is an odd number. You don't require an Arbiter.
Unlike Microsoft clusters, Mongo's cluster voting doesn't care about multiple avenues of network to break voting deadlocks. Because of this, separate arbitration and cluster-internal networks do not provide any meaningful increase in robustness. The only reason you'd want a separate arbitration network is if replication traffic was expected to be so heavy that election-packets (the heartbeat, actually) would get pushed so far down the stack that it would miss the 10 second timeout.
Best Answer
The answer to your question is that it is not possible to do with only two locations.
The reason it is not possible can be explained like this: If both locations are fully functional, but the network connection between the two is faulty, only one of them may remain functional. It is not acceptable for both locations to simultaneously elect a primary in this case.
There is no way for one location to tell the difference between the other location being completely down and the other location being up but the network connection between the two being down.
So if each location independently could elect a primary when the other location was down, the consequence would be that in case of a network outage it is possible for two primaries to exist simultaneously. Having two primaries is an unacceptable scenario, and this is why only one of the two locations would be able to elect a primary.
Having three locations will be sufficient if you make assumptions about the behavior of failures. Any solution that works without making assumptions about failures will require at least four locations in order to tolerate the outage of a single location. This requirement follows from one of the key theorems in the area of byzantine agreements.