Outlook Pipeline - Error Remote Service

Yes to your first question - you would need to add the additional file attachments as field to pull in your pipeline so that you can use them in later steps. You would then list each file on a new row as Manny provided. 

To your second question about the filter, if you add them to that filter condition and lets say you have 3 attachments, then you would need to have all 3 files present to send the email. If thats the desire then yes you would add them as conditions there. However, if you still want the email to fire if a subset of 1 or 2 files are missing then you will likely need to employ some Jinja {% if %} syntax to handle including files provided that the Pipeline will throw an error if you tell it to include a file attachment that does not exist on a record.