EV service accounts

When you say within an organization, generally we deploy single Directory EV with multi site which should work fine with same VSA.

We decided to have mutiple deployments as our datacenters are geographically far apart and that we didnt want EV services in one region depdendent on the other. It was also decided based on documentation where it was mentioned that the EV server will communicate to Directory database frequently during archival and retreival and we didnt want that traffic to happen over a WAN link with 100 ms + latency when archiving 20K mailboxes. 

So, does it matter if we share the VSA across multiple EV deployments?. Will there be any conflict?

no it does not matter, i have seen quite a few organizations have multiple EV Directorys and EV Sites and use the exact same evadmin without an issue, and if you use Discovery Accelerator and want to search all those sites, using the same EVAdmin is a good thing

Is anything else needed with this issue?

Great news.