We also have a field named "Primary?" indicated with a (Y/N) button corresponding to each email address. Is there a way to use the "primary?" field to select one email address to export?
Yes. You can define relationships that match more than a single pair of fields. Define a new field in your main table that returns "yes", (I'm assuming that your Primary field is text that contains "Yes" if that radio button is clicked.). Name it "PrimaryKey".
Create a new relationship linking two pairs of fields: MainTable::ID = EmailAddTable::ID AND MainTable:: PrimaryKey = EmailAddTable:: Primary?
Creating this relationship will also create a new Table Occurrence for your EmailAddTable. Name it "PrimaryEmail".
When specifying fields for export, select PrimaryEmail::EmailAddressField and you'll export just the primary field.
Each email address has a corresponding type ID field (work, personal, etc.). Could we somehow use the "type" field to select which email to export?
You can use the same approach described above, but using the "Type" field instead of the "Primary?" field.