I would like to create monitoring tool for events bandwidth for all profiles. I've read the is a possibility to get this event data information through the EventStore, but is there any way to connect EventStore through the Rest API endpoint if yes - where can I find details about it. Is it also method to capture event data from all profiles for monitoring purpose ?
There isn't currently a public API to return Event counts for profiles. You could log a Tealium Product Idea for that here - https://community.tealiumiq.com/t5/Product-Ideas/idb-p/product-ideas
EventStore doesn't report a count of Events, but rather is a store of the incoming events themselves, so I don't think it's what you are looking for here.
Just in case you don't know about it, there is already built into CDH a report of event counts by profile, and for all profiles. When you log in to CDH, look for "Data Supply Chain" in the left hand nav, and then click on "Usage Reports"