@dev-cb I know you've already swapped, but wish I had seen this a few days ago.
I run a slightly older version of Directus locally, but at least in it...
(1) Repeaters can't reference collections. If you want to reference other collections, you have to create a relationship (like Many-to-Many). Which is not quite as convenient, but a bit more powerful.
(2) As far as I know, nope. For this, you have to manipulate it in Gatsby. I do my manipulation in Elder.JS.