Adjusting dessert recipes to accomodate a larger slow cooker

It's definitely asking for rolled oats, not prepared oats. It's just like oatmeal cookies.

It's up to you whether you use normal rolled oats, quick-cooking, or instant. I use normal in my crumbles, but you might choose quick or instant if you think the normal retain too much texture. Personal preference! They'll all work, though, so you can just use what you've got on hand.

(When I do oatmeal for breakfast, I prepare normal rolled oats as if they were instant - just add boiling water. I like some texture.)

And while I'm at it, general advice: crumble topping is something you can easily do without a recipe, just throwing in the ingredients until it holds together a bit, but is nice and crumbly. So don't worry too much about exactness here. It'll come out great.

Salt has unique properties in how it interacts with the taste buds. While it has its own "flavor" it also has the ability to enhance some flavors while blocking your ability to experience others.

While I could go on, all I would be doing is repeating much of what I learned watching The Food Network's Alton Brown. He goes in depth for the episode "The Ballad of Salty and Sweet" which is available on from the Food Network.

There are (of course) other resources, but AB does a really great job of teaching in this episode.