Re:Quality Engineering Help
Being one of many to whom the English language came later in life, I believe that I might be able to understand, and hence answer, your questions. The answers cannot be shrunk to a page each, so instead I am pointing you to different sources.
The answer to your first question, on how to manage successive versions for documentation, will be found in http://en.wikipedia.org/wiki/Revision_control
This also, at least partially, answers question 3, on products for traceability. More on this later.
On question 2, managing the tasks that are being currently completed, we see a lot of MS Project being used. In other cases Issue Tracking Systems (where you previously enter EVERY task as an issue until it completes) has been used successfully. Some such tools include Clear Quest (on the expensive side) and Bugzilla (shareware, open software that you can tailor to your needs).
Question 3 is about traceability from use cases to tests, and it should be through every other work product in the life cycle as well. Enterprise Architect (http://en.wikipedia.org/wiki/Sparx_Enterprise_Architect) is a reasonably priced, high efficiency tool that I see used with great success. Other tools include Rational Requisite Pro, ERWin, etc.
Lots of luck.