I don't know how to make new articles...
The simplest way to create an article is to follow a link to a page which doesn't exist. You can also use Search, which will result in the text "Create the page "[search terms]" on this wiki!" if no match is found.
Once you're editing the blank page, it's sometimes easiest to copy the formatting from another good page and change the specifics. For instance, if I were to create the article about the Soybean, I'd probably copy an existing page about a Pam's HarvestCraft crop, such as Asparagus. If you're familiar with our templates and standard page format, you can also just write the article and include the infobox, navbox, etc from memory.
Preview, Save, and you're done.
Is there a standard way of updating these pages from one version to another? For example, I'd like to update the Crackpack page on ATLauncher wiki, but there have been some big changes between 1.5.1.0 and 2.0.0.0, and I don't want to mess anything up.
I'd think it would probably be best, at the moment, to document the 1.7.10 version as The Crack Pack 2. Brand new page to differentiate it from the 1.6.4 version.