i would add cocoa during the last 10. Fruit is usually added in secondary. I did AHB Choc rasberry stout but used real berries in secondary and it tasted like ass as of 2 months ago. Its been sitting for a while and mellowing but i used 1 Lb rasberries per gallon and i would have been better suited to use maybe 1/2 lb per gal. Very tart and offputting but its slowly getting better.....You could use malodextrine for mouthfeel instead of oatmeal. Thats what i usually use because i have yet to mash with oats.
On Hiatus: Brewing at work....