Extracting indiviual files or directories from XYZ.tar.xz - Possible?

[Richard Owlett <rowlett@access.net>]

I'm too acclimated to decompressing with single mouse-click ;/
Where would I find a good introduction to tar archives?

My situation:
I expressed dissatisfaction with the internal "HELP system" of my 
preferred browser.
The senior maintainer pointed me to the source archive and identified 
the directory containing files of interest.
Though analog oriented, I have decades of customer service, QA/QC, and 
engineering support.
I accepted the implied challenge to "Put up or ..." <*GRIN*>

I have two primary goals:
  1. Convert the content of the current "Help system" to a set of
     HTML files. The maintainer that's reasonable if tedious.
  2. Test ideas I've had for making large HTML files conveniently
     accessible to a specific set of the visually challenged.

My questions:
  1. Can individual files or directories be extracted from XYZ.tar.xz ?
  2. Is there a compressed format that makes above convenient?

TIA