For your first question, dynamic segment refresh once an hour and we couldn't adjust it.
For the second:
As doc introduced, this tile is to track an enity's associated contact, so the entity(Entity name setting) is main part, which means we could set any entity that has a field(lookup) associated with contact instead of only contact, the associated contact will receive email when we create/update/delete this entity.
For example, my tile properties is below:
When we update Address 1: City field(1), the primary contact(2) of this account will receive email.
For your settings, you are going to send a contact's associated contact,
as description for this field in Metadata Browser:
So you could check whether this field has value when you update contacts.
Regards,
Clofly