Yes, EP configuration has a setting called as 'Subject Filter' under Inclusion section. Here you can add multiple keywords seperated by ";". If this filter has been specified then [...]

Yes, to set up default values...select data source as "Default Values" and then enter the text accordingly. For example, if you wanted to set a default value for "lead [...]

Yes, the regarding field in email is set to the newly created record. You can view the email in the activity section of this record.

Below CRM field data-types are supported: Single line text Multi-line Text 2 Option-Set (yes/no;true/false) Option-Set Date-Time Currency Integer Decimal LookUp