A wise choice! Of course, we're always happy to have another set of hands, eyes, and brain lobes working on this project-cum-timesink of ours. First, visit the Contributing to Horde page for general details. Next, make sure you're on the appropriate mailing lists; you should certainly be on the dev list, and probably on the bugs and commits lists if you're working on something that's being worked on by others. Of course, you'll also want to be subscribed to the list dedicated to the component you're working on. Once you've subscribed, post a short note mentioning what you're planning on doing, to make sure that you're not duplicating someone else's work, or reimplementing a feature that was just recently removed! After that, check out your components from the Horde Git repository, and start hacking!
We're not sure. Those that know aren't telling.
Seriously, many of the components have somewhat awkward acronyms as their names, such as the Internet Messaging Program, or the Web-based Horde Unified Project System. The maintainer of the FAQ has a suspicion that others were pulled at random from an IKEA catalogue. Besides, it's more fun to let you guess.
No, they are not. See, e.g., one of many mailing list discussions on the origins of ther terms. Simply put, "blacklist" and "whitelist" are the most concise terms we can use to accurately describe the underlying filtering mechanism. (If you can think of a more precise term, let us know!)
In all truth, The term blacklist is a derivative of the term "in one's black book." this term was used most notably by Henry VII and Joseph McCarthy, although by countless others for various reasons, to denote those out of favor with a given class or group. It was intended to imply that those listed were people who committed unfavorable or devious acts in the cover of shadow, and It's probable first use was in the reign of Charles II, with reference to a list of persons implicated in the trial and execution of his father. The term has been used for hundreds of years to denote those who were boycotted or disallowed because of their social standing or their actions. This etymological history in no way indicates a racial origin.
If you want to change the terms on your local install, see our documentation on how to change phrases.