Sure you can, its your beer.
I would ferment in primary as one batch for 2-3 weeks. Then bottle the first 7L. Split remaining beer into 2 secondaries. Add coarse ground coffee beans in dry hop mesh bag to 7L for 2-3 hours (0.5 - 0.8 oz of beans should be enough). Gently swirl the beer up and taste every hour or two to make sure you don't go overboard.
Add your cocoa addition to the other (I have no experience here on how or what to add).
Primary #1: Big 50 Barleywine #2:Empty
Secondary #1: Peach Rhubarb Wine #2: Empty #3: Empty #4: Framboise Lambic
Kegged: Pumpkin Ale, Orange EPA, Piker Liker Porter
Bottles: Red Rye IPA, Dark Belgian Strong, Belgian Golden Strong, Kicked by a Moose Scotch Ale, Apfelwein, Russian Imperial Stout, Carmelite Tripel, Rhubarb Wine, Barolo Wine
On Deck: Umlaut my Kölsch V