showing live points on a map and managing edits by different users

I am using node/express + mongodb for the backend of my app.

I have a map with hundreds of points. When a user click on a point, a panel on the right side allows him/her to edit the point properties (around 15 of them). The user can also add new points.

Could you please give me some advices/best practice on how to best manage : 1- concurrency edits 2- the live display of new points

I have never done this before... should I refresh the list of points with ajax every x seconds or use something like socket.io ? How should I design my mongo document to "lock" it during edits ? How to explain the user that a document was modified while he was editing it ?

It seems complex as a beginner but I suppose this use case is quite common ?

Thanks