I use a VitaMix, so stuff is more than fine enough to allow nutrient absorption.
Easy to see if they're being broken down--same way you can tell if you've been chewing your corn.
Cooked oats are more likely to be absorbed because they don't require as much processing (chewing, digestion) as raw oats. The size of the pieces also matters; more surface area equals easier digestion--one reason we have molars.
I don't use a "huge" amount (I think I was using about 1/2c uncooked?) and I noticed it added a slight "dusty" flavor, but it was not particularly unpleasant; I actually kind of liked it but when I use it as part of a drink now I use about 1/4c, just for a boost of some middle-of-the-road carbs and fiber.