it's a pretty ridiculous security vulnerability that skype leaks your ip, which has far worse consequences than being ddosed in a video game. given skype also has government backdoors and is monitored by microsoft, i'm not sure why people still use it instead of other, superior alternatives like mumble.
in any case, awesome guide. it's worth mentioning that some vpns, e.g. http://btguard.com
, provide "torrent-only" proxies, which is basically just a socks5-only proxy. you can configure skype and firefox to use it just the same. the same goes for tor, but tor probably isn't fast enough for voip.