It's like "cooks-do", as in the sentence "Cooks do cooking for their living". Actually, it's the literal transcription of some German slang meaning "Look at that!".
Yes. qooxdoo is Open Source, dual-licensed under LGPL/EPL, i.e. the "GNU Lesser General Public License (LGPL)" and the "Eclipse Public License (EPL)". As a recipient of qooxdoo, you may choose which license to receive the code under. More licensing info.
Yes. Always has, always will. It is a true Open Source project: standard licensing, contributor-friendly, public code repositories, public bug tracking and roadmap planning.
No. It was registered as an Open Source project at SourceForge on January 2005, one month before the term "AJAX" was even coined. It is constantly being developed and improved, which makes it one of the most mature and innovative web application frameworks today.
Use the general mailing_lists. Many active users as well as the full-time core developers try to answer all your questions. There is no commercial support currently available, but there are several companies listening to the mailing list to offer qooxdoo-related contracting.
While several books contain sections on qooxdoo or references to it, you cannot buy a printed book just about qooxdoo. Use the qooxdoo manual instead with its approx. 400 pages. It's available for free: as an online HTML version and a PDF to download.
A qooxdoo application runs in all major web browsers - with identical look & feel.
No. If you already have an existing backend that serves HTTP (or HTTPS) requests, it's probably fine to continue using it. Optionally qooxdoo offers several RPC servers for an elegant client-server communication. BTW, during development of your client application the local file system often is sufficient, without the need to use a real server.
No. It's also not just a "library", but a "framework". It is much more comprehensive than a typical JS library like jQuery or Prototype. qooxdoo's main focus is on creating full-featured rich internet applications (RIAs), so it comes with a large set of high-quality widgets and features a powerful, platform-independent tool chain. But due to some recent advancements it is now also possible to leverage qooxdoo as a low-level library for extending traditional HTML documents.
As with other typical JS libraries, much of jQuery's features are a subset of the qooxdoo framework. To allow for a jQuery-like programming style, an API very similar to jQuery is provided.
Only to some extent. There is no official GUI builder that comes with the framework. But there are some community-driven attempts to create such GUI builders. These contributions may have different objectives and may only work with legacy qooxdoo code, so YMMV. If you're interested, have a look at some of the following implementations: Tartan Blueprint or qooxit for some fairly recent attempts. jsQt for a Qt Designer based solution. Older attempts include Weida (browser-based, contributed), PyQooxCard (part of the QxTransformer project) or GUI RAD for qooxdoo. A commercial solution is Delphi for PHP from Borland/CodeGear (frontend largely qooxdoo-based). qooxdoo's built-in Inspector is a sophisticated debugging tool rather than a GUI builder, but it might help nonetheless as it allows to manipulate a running qooxdoo user interface.
Yes, several. Java-oriented are QxWT, which provides a qooxdoo wrapper for GWT, or the Eclipse Rich Ajax Platform (RAP). An XML-based UI description is featured by QxTransformer. A visual RAD solution is Delphi for PHP. See some more solutions.
The homepage is a Wiki, that allows you to easily modify its content. You are welcome to contribute. See here for more information.
Absolutely. You are invited to become a fellow developer and contributor to the project. There is an infrastructure for contributions, which allows for easily setting up, developing, releasing a project and for collaborating on it.