You might have the best luck mashing just the oats and 2 row, and then steeping the dark grains and crystal malt. All the dark malt will dilute the enzymes and lower the pH. You just barley have enough 2 row to convert the starches in the oats, so I wouldn't push it. Otherwise the base recipe looks fine.
My personal preference for chocolate flavor is to use cocoa powder, mixed with a bit of hot water, and added to the secondary for about two weeks. The fat in the bakers chocolate can cause problems, although many people report using it with success. For coffee I like more aromatics, so I've found adding it for ~24 hours right before bottling gives me the best results.
Hope that helps, good luck (hope you aren’t planning on drinking much of it until next winter).