As far as how everyone is multi-tasking or kept to a specific role, it's pretty fluid. Everyone has his or her general domain of expertise, but because we are small, we can bounce between different things. It's unsettling for some of us to start, but we've gotten a lot better with managing projects over the last couple of years, so that we know what we are working on for short sprints, and we know what our overall roadmap looks like. So the thing we do is to try to plan often, and work on things sprint to sprint towards milestones we set for each project. The trickier parts right now, with co-op about to have a first integrated prototype build, is to plan out how user experience is going to flow, how progression is going to work, and how anything user experience, progression, or design wise is going to affect what we do for Skirmish, or more importantly, how anything we do in Skirmish is going to affect co-op.
But like Queso, Imagine, and a few others mentioned, sometimes we have downtime or spare time, and when we do, we'll jump on something else and do a quick sprint on it. The Hamsterdam work over break was a good example. But this I try to manage as best as we can. By the way, for school or team projects, we've been using this online project management tool called Trello. Not sure if you guys have checked it out, but it's awesome. It's based on kanban, and really easy to use. You guys should check it out. But yeah, trying to manage all the moving pieces sometimes is a challenge - fun, but stressful.