No problem
shokan and I totally understand your uncertainty and lack of clarification within regards to Usenet - pretty much the same here mate.
It sounds like you are primarily seeking some pretty specialist topics, and of course digital tools such as Zbrush have a hefty niche on the Newsgroup scene.
I'd seriously take a day or two and step back from the "I want to get this...." question we all inherently have and take some time aside from your topic of interest to look at some Usenet guides before you take the plunge.
A really good starting point over a beer and some quiet time would be :
http://www.slyck.com/ngnew.php
Once you have taken all that in you might be in a better position to detail more specific queries on these boards.
It seems like a lot of reading, and it might seem a tad against the "grrrr I want it ALL NOW" syndrome but trust me if you are posting about uncertainties over NZB's then you would be very well placed to take a few minutes out to do some research.
As much as I could sit here and type an "answer to question 1" I do not think it would help you much.
Hit slyck and do a bit of reading based on their links and I honestly think you'll thank them for it. It will give you a good start, and answer a lot of simple questions that fund the basis of Usenet and will put you in a good position to prompt specific queries more experienced folks here can help with.
You've made the first step, and you are clearly interested in academic queries so I am sure a night reading up on the basics will serve you well.
Simply put, I see what you want but I think we could spend post after post getting nowhere without you spending a very small amount of time getting to realistically understand Usenet protocols - at the very simplest find out what an NZB file is and you are here forever mate.
Not immediately useful but I think it is words well spent on all Usenet newcomers.
If I sound like a condescending git then I have no intention of being one, I am just trying to help in the longterm.