1. Why do they object so much when 99% of everything that is published on the web has been in the public domain anyway, i.e. in Watchtowers, Awakes and other literature whaich are distributed free of charge?
Because they want to control the conclusion the readers come to. This is why they insist on holding one-on-one studies with new people. It is a form of brainwashing.
2. Are any of the older books, e.g. by Russell and Rutherford still covered by copyright or has this now expired?
Yes. The copyrights for ALL of Russell's and Rutherford's books have expired. Anyone can reproduce the books in any quantity they want.