Russell was addicted to medical books published for the public. These included suggestions on home treatment some of which are banned today, or just silly. He was not anti-medicine. In fact a number of his prominent followers were physicians.
The anti- and quack- medicine views came from the Golden Age's editor who read among other authors Bernar McFadden. Russell did not share those views. This is a product of the 1920s. In Russell's day medical practice in the USA was divided into several strands: Ecclectic, Homeopathic, Allopathic [today's MDs, the term is now considered pejorative], and Herbal. Barbour was an 'electric physician.' This was seen as valid medical treatment in that era; several of Barbour's advertisements for his medical practice exist. Russell was attracted to advice from all of these. Russell considered manufacturing and selling a common remedy [Compound Oxygen] for the benefit of the brotherhood but decided against it. This was prompted by John Corbin Sunderlin's claim of relief from chronic pain, the result of Civil War wounds. A letter from Sunderlin to the maker of Compound Oxygen was used as an endorsement by the company.
Yes, Redding got it from Russell. An Advent Christian writer also pointed to 1914, but seems to have gotten it from Elliott's Horae. Others included things Russell wrote in their own writing without being Russellites. This wasn't as uncommon as one might think. In the late 19th and early 20th Century it was not exceptional for religious people to think they were God's mouthpiece. But each of them borrowed ideas from others. In Russell's case some call him a plagiarist. He does not, in my opinion, reach that level. But he was influenced by others. And this includes his views of medicine.
In the Russell v. Russell transcript he talks about treating members of the Bethel staff with remedies. These were derived from physician-authored books such as R. V. Pierce's Common Sense Medical Adviser in Plain English; or Medicine Simplified. These were printed by the hundreds and advice from them appeared in almanacs. Russell did not reject medical practice.