If they are on the same iTunes account, apps already purchase for the kids should install to the Touch. While there might be a limit on number of devices to an account, I think it is at least 5.
My daughter's family has an iPhone, three Touches (gen 3 and 4) and two iPads (different generations) sharing an account and a music library. Each person has the apps, music, books and videos they prefer, though they've come from a single account. I think each device is still using the iOS version shipped with it, my SIL is not much into dealing with system upgrades.
I use iTunes on PC to manage what goes on to each device (I have only two so far) and manage my music library, but I think you can now do much of this on iCloud.
My grandson was fluent in the use of his aunt's iPad, and my iPad, and was extending that experience to the exploration of my iPod Touch, four months before his second birthday. But he had little prior computer experience to confuse him. When I went to the AT&T store to look at an iPad, while I was staring at it trying to figure out where to start, a toddler pushed past me, opened the menu, searched out her favorite app and started playing it.
People coming from Windows (my mother, and a couple of friends in their 80s and 90s) struggle with the change of paradigm. But I understand that, been through it in several phases, my first coding was in binary, an assembler was a big step forward. 30 years later when they put graphical user interfaces into our Unix and VMS environments, first thing us old hands would do on logging in would be to open a terminal window and start typing in commands.