Hardware:
Decent rig for efficient rendering times/quality. Minimum 2 harddrives, one for running your os/game and one for recording to. You should have one drive doing nothing but recording with at least a 250gb capacity to be able to record for decent periods at a time. The most important parts to sink money into when it comes to rendering is your CPU, your GPU and your ram. I recommend a mid-end Intel or top-end AMD, nvidia gpu for better rendering enhancements to things like Premiere Pro, and a good 8 gbs of ram or more. USB harddrives may cause issues when it comes to recording, but USB 3.0 isn't too bad. I use a 500gb USB3.0 portable harddrive dedicated to recording. You will need a decent USB or XLR microphone aswell, I recommond the Samson Meteor and Blue Snowball for under $100 and the AT2020 for above $100.
Software:
I recommend Photoshop and Dxtory no matter what. Dxtory to record your games, Photoshop for photo editting. The actual rendering software is where you have some choices. I recommend Premiere Pro, After Effects and Vegas Pro. A great free software for audio editting is Audacity.