As for how we know which Contacts belong to which Accounts we have a few ways of doing it:
Once that's working, following Accounts works just like following Contacts.
Total events is a snapshot of how much activity the account has had over different time periods with change metrics included.
In addition, we show events over time for the account as a whole:
There are a number of activity modules displayed on an account page. This includes the active contacts chart, which shows you how many contacts from that account performed any activity over different time periods.
Accounts in Variance have Properties. This is where you can store information about the Account. You can update these via Segment or Rudderstack and from your CRM via Zapier. You'll also notice the domains associated with the Account under the name.
We know that it's hard to always have data stay clean, sometimes two of the same account or contact show up. You can merge those together in a non-destructive way that will simply tell Variance that all of these Accounts and Contacts are the same.