Site for different locations, where to read?

Question

Domain Name System

Good afternoon, there is not a big project, it works for several countries in Europe, the CIS and Russia for these purposes, the site is located in a DC in France, everything is fine.
Not so long ago we decided to cover the US and Canada, a server on the border of Canada.
Now there is a problem with fussing with different versions of sites and the fact that they have to be managed separately, we decided to combine sites, the questions arose:
1) Where to read about DNS Load balancing via Geo-ip, something similar, can you tell me existing services, the task is simple, throw a person nearest location?
2) How to properly organize work with the database in this case and avoid large delays, because both servers can add data (data is added less often than read)?
3) Also, ElasticSearch is used to search the site, in our case, should the instances be duplicated or left on the same server?