Some of the stuff looks out of date.
Before anything else, there's a new way to package up skins. It makes packaging skins up much more useful. I described it first in a tutorial:
http://blog.redwerks.org/2012/02/08/mediawiki-skinning-tutorial/
And we're ready for people to start putting their skins into real repos instead of passing around out of date tarballs.
Skin developers can request a mediawiki/skins/{skinname} repo. And commit their skin to there. And they should be able to get the same — i18n (TWN might need some tweaks though) and support for new things — advantages that extensions in our version control have.
We also have a Skin: namespace ready and available on the wiki for skin pages.