How to configure OpenStack Swift on a geographically distributed system?

Question

Distributed Computing

I am writing a thesis on the topic "Modeling a distributed computing system S3-storage". I need help from OpenStack Swift specialists and the platform as a whole, otherwise I'm completely confused in it. Recently, one of my test servers died, and therefore I don’t have the opportunity and time to figure it out myself.
Some input:
- In my example, there are 2 "regions" from different cities, each with 4 "zones", each zone has one device;
- Each region has one proxy server;
- The machines are running Ubuntu 12.04 (if that's important);
So the questions are:
1) For the functioning of OpenStack Swift in general, is it necessary for me to build computing nodes on which to install nova, keystone, glance, etc., if I only need storage from OpenStack? If so, why (can be explained by references to foreign resources)?
2) Where are Swift proxies usually located: on a separate machine, or on the same machine as the storage nodes?
3) Can storage nodes from different zones be on different subnets?
4) Can I build such a model (2 regions, 4 zones, 3 replicas) on VirtualBox virtual machines and if there is a VPN connection between the regions? (this question is very important, because, again, I don’t have time for experiments)
ps in case the question seems silly to you, I will immediately make a reservation - the level of my knowledge in cloud systems is 3 with a minus, or maybe less