Re: good recording software?
There are tons of DAWs out there for recording and editing audio, ProTools is the industry standard but Cubase is popular too. It just depends which workflow you prefer, I use Ableton Live personally. Also you don't need an interface for midi, all these programs have built in midi capabilities, you can pretty much do anything you want with it.
However I would look into getting a new mic as well, if you're concerned about quality then a USB mic is a no go, it's XLR or nothing. Shure SM57s are fantastic for guitar, but they're very pricey too (worth it though). That's when you would need an interface!
Your music sounds cool man, any more questions just ask!