As far as employment, there's a lot of stuff going on. Traditionally aerospace (where you'll see the super hard-real-time mission critical stuff) is a PITA because they know the work is desirable and can therefore pay peanuts for people to do it. That's changing though so keep your eyes open. Also, don't do anything that could jeopardize your ability to get and retain a security clearance if you're US based. You'll need one for a lot of those kinds of projects (though not all).
Finally, get used to process. If you do critical work, the more critical, the more process you have to follow. Lots of code reviews, heavy handed version control rules, design and deployment paperwork, etc. It's not bad but it seems to be a shock to everyone.
If you have specific questions, feel free to contact me at gmail.com. I have a couple other responses in this thread that might also be useful to you.