The Mk 108 is a Autocannon. Those fire explosive or armor piercing ammo at full auto speeds. http://en.wikipedia.org/wiki/MK_108_cannon I say +1 to having them Also, the autocannon goes 'Boom boom boom' the GAU goes 'BRRRRRRRRRRRRRRTTTTTTT'
Assuming that it doesn't need to go to space: A danny-class launcher. Fuel tank and mailsail upside down, fires a probecore + chute + kerbal up in the sky Assuming it does: Single mainsail + rocko tank to launch a sat.
Also, I woudn't recomend Ubuntu, but Mint for a beginner. Reason: http://www.howtogeek.com/208070/new-to-linux-dont-use-ubuntu-youll-probably-like-linux-mint-better/