To add records using a Portal, go into the relationship graph and edit the relationship for the Table Occurence for the Portal. Click the check box for "Allow Creation of records in this table via this relationship" Close the manage Database window and then on the layout for the portal clicking into the last row in the portal will create a new record in the table. That is what the script you does.
Another option is to have a script that changes layouts, then executes a new record script step and fills in fields.
No. The relationship should be one-to-many. But in Filemaker there is no difference in how you would configure a one-to-one and a one-to-many, so that doesn't really matter.
To make this work you need a "parent" table, like Research Detail, and a "child" table, Notes. Make a relationship between the two. The Research Detail table should have a unique ID field, and Notes table should have a Research Detail ID field and you make your relationship between those two fields. Check "Allow creation of records in this table..." checked for the Notes side of the relationship.