Okay, so I'm going to brew two semi-different 5-gallon batches of an oatmeal stout (one partial, one AG). Since I don't really want 10 gallons of an oatmeal stout sitting around, I wanted to make some slight variations. I was thinking of taking 1-2 gallons of each (into a separate secondary) to make a blueberry oatmeal stout and a coffee oatmeal stout. I plan on using real (crushed) blueberries; I will crush them so the sour skin won't reflect in the brew. I also plan on just using some regular grounded coffee (possibly a decaf hazelnut).
My questions are,
1) How much blueberries should I crush/use for 1 gallon of beer so the blueberry taste is noticeable in the brew (above just a vague/mild flavor)?
2) I plan to cold-brew the coffee (I think?) by grinding the coffee beans ([a] how much grinded coffee should I use for 1 gallon of beer?), letting it sit in water ([b] How much water should I use?) for 1-2 days, filter the grind/beans from the coffee/water, and then put the cold-brewed coffee in my secondary to be racked onto.