I can't help you on the Buchan Observer but another resource to try is the Aberdeenshire County Library headquarters in Oldmeldrum. Also try searching on Google. I found the following:
James Strachan [Strahan], was born 1st May 1863 Fyvie, the son of John Strachan. He was appointed as the Minister of the Free Church of St Fergus as Mary already mentioned in a previous response, located in Shielhill, in about 1893. He was much published. He attended Aberdeen University as did his brother Dr Robert Strachan, b 4 April 1864, Fyvie & later of Wilson College, Bombay.
Your James Strachan's appointment appears to have been reported in the Aberdeen Weekly Journal Wednesday, April 23, 1890; Issue 10987. There appears to have been an Action for Slander against him while he was at St Fergus in 1893/1894 much reported in the Aberdeen Weekly Journal. Try the Aberdeen City Library for copies of this. However, a faster route would be to try the British Newspapers database 1800-1900 - available free in the UK via a University library. Depending where you are located, also available via your local LDS family History Centre or online for a small day fee via Gale Databases online http://newspapers.bl.uk/blcs/start.do.
There is a book called "The county of Aberdeen" By Henry Hamilton pg 304 which mentions the Free Church at Sheilhill. A Preview version is on Google Books.
In 1903 James Strachan was appointed the minister at Belgrave Presbyterian Church in London. He eventually became Professor of Hebrew at Magee College in Londonderry where he died 1926. So lots more areas for research.
Last but not least, as he attended Aberdeen University, the Aberdeen University Review v. 13-14 - published 1926 - has a write up on him on pg 288. He is also mentioned in the 1938 edition.