Once you have that installed, running news.arc is detailed in a rather simple text file labeled how-to-run-news. Edit: Note that it's not quite the same version that is running here at HN; pg has modified this version slowly over time.
Ah, I've only recently begun to overcome that myself. Even though the docs at files.arcfn.com/doc are a bit dated (they were written at version 2) I found them to be one of the only resources besides pg's minimal tutorial. You could also try anarki as well; it has a useful help function that prints some documentation for many of its functions and macros. You can clone the anarki repo from github.com/nex3/arc.
how the requests are handled
Look for the defop statements in news.arc. I don't know news.arc as well as I know the blog.arc file, but there's probably a statement that begins with something like
(defop news req
There should be a variable defined in news.arc named
Hope that helps; I know the community is kind of a mess for arc.
Would you know of another less painful, very minimalist, web oriented lisp dialect?
Unfortunately, no. As much of a joy as it is to program in Arc Lisp, development of the official branch seems dead and I have some doubts about anarki's stability.