2: It depends on every company and how many people are on the team, but you can set up a sequence that will create emails to contacts and tasks for the users associated. ( More information here ) ,
3: As a standard, once you create a sequence HubSpot will show a default sequence that you are able to customize to fit into your company.
Sequences templates
4: If the contacts are not responding to a sequence, since you can only create tasks for yourself in the sequence and it's based on a Sales feature.
I will be tagging some of our top contributors into this conversation, @daviddoughty,