Now seriously, as a software developer, what would be the best skill set to help these guys... As soon as I can afford it I would knock at their door and work for them for free. What would be most usefull for them (or spaceX)... A lot of C, C++, knowing NASA's open source repos in and out, doing MIT online courses on robotics and astrophysics... ?
Why don't you write to SpaceX and ask them what skills they are looking for? Once you work for one kind of space company, you can probably get into another one quite easily.