>>12You can make some damn alright chipmusic with the following:
OpenMPT – good, simple tracker. Find some samples or VSTi's or whatever and get cranking
Famitracker – Wanna make NES, Famicom, or Gameboy (not designed for gameboy but you can essentially do it anyways) chiptunes? here's your basic tool
MuseScore – cheap and simple way to flesh out some ideas if you're used to using a staff. Then go from staff -> tracker or whatever using a different program
Audacity – shitty but free and good for final touches and simple finishing effects
FL Studio/Ableton/pick your poison with a decent VSTi like this
http://www.tweakbench.com/peach works too
As for composition, learn basic theory and focus primarily on using a limited number of tonal voices effectively I guess