Windows?
Xnews is freeware:
Agent is buyware:
http://www.forteinc.com/main/homepage.php
Both will be fine with 3000+ days in a txt group or low traffic bin group. Not sure how either would cope with a really high traffic bin group.
Yes you can access individual newsgroups with any usenet provider.
What you need to do is to find a news reader which accesses the specific newsgroups, for example Forte Agent:
I have no idea how you would do it now, other than getting a copy of Agent 8 and downloading headers for the groups you want to follow. I stopped downloading headers years ago when NZB files became a thing.