Brown Cow is a good brand, I buy it sometimes too.
For myself I really like their strawberry and blueberry yogurt.
How much to feed depends on the size of your individual dog and the total amount of calories he/she is eating per day. And of course the size of the Kong you are using.
My dog weighs 28 pounds and I don't feed more than about half a cup of yogurt at a time, and I include it in the calculation of his daily feeding amount.