Hi, 1. Nancy Minerva Scott was born abt. 1831 in Pennsylvania. I didn't find her death info on-line, however, she appears in the 1880 Oakland, Alameda Co. Census. The following web site has information about searching for death certificates in Alameda Co., cagenweb.com/alameda/Pages/ResearchToolkit.htm.
The County of Alameda Clerk-Recorder's Office is at acgov.org/auditor/clerk/ .
Birth and death records weren't required on the state level until 1905 so you may or may not find that information in the County Clerk-Recorder's offices.
I searched for David Allison McKinley's death info on-line but didn't find it either. However, I did find the Montana Porter's Family Tree which contains the McKinley family, trees.ancestry.com/tree/6431934/person/-648833589 . They show he died 18 Sept. 1892 in San Francisco, San Francisco Co., CA.
This info should be verified by ordering a copy of his death certificate from Office of County Clerk, www.sfgov2.org/index.aspx?page=64 or a copy of his obituary.
Go to freepages.genealogy.rootsweb.ancestry.com/~obitl/volca.html for access to other web pages where you can order a copy of his obit or look up deaths and obits in San Francisco.
2. I searched for them in the 1870 Census in Ancestry and FamilySearch but didn't find them. If David was mining aways from civilization, they might not have been enumerated on a Census.
3. I didn't find any indication that they had a child named Gibson but there are too many gaps in the Censuses to know for sure.
4. Ida Helen ---- She and her family in 1900 were living in San Francisco, San Fran Co. George Morse, b. CA Aug 1870, marr 7 yrs, clerk A. S. D. court. Ida H., wife, b. CA Oct. 1870. Marjorie M. Morse, b. CA Feb. 1895. Katherine M. Sebula, servant. Minnie Korbir, servant.
In 1910 Ida was married to Harry R. Cooper and living in Oakland, Alameda Co. Harry R. Cooper, b. CA, 42, M1=5 yrs, stationer own store. Ida M. Cooper, wife, b. CA, M2=5 yrs, had one child who was still living in 1910, father born=OH, mother born=PA. Majorie Cooper [what appears on census but should be Morse], b. CA, 15.
I found this because of a note on the census that another Ancestry member had made. You should order a copy of their marriage cert from either San Francisco Co. or Alameda Co.
A Marjorie McKinley Morse b. 25 Feb 1895, San Francisco, San Fran-- Co. married Dec. 1912 Emanuel Villard Heidt in San Francisco City. She died in 1935 in San Jose, Santa Clara Co., CA. Source=George & Lara Monroe Family Tree, trees.ancestry.com/tree/14933020/person/185497044 .
An article was in the Oakland Tribune on April 22, 1913 about Harry Cooper laying claim to the late President McKinley's personal effects. Harry claimed that Ida had sold the articles to him and Marjorie didn't deserve them because she hadn't taken care of her mother properly.
Therefore I believe that Ida died about 1911 or 1912.
I found more information about Marjorie and her family if you want it.
6. I believe that William Perry Francis McKinley died in or around El Dorado Co. He wasn't mentioned in any other Censuses and I didn't find him living alone in other Censuses.
There is a Random Acts of Genealogical Kindness volunteer in El Dorado Co. Go to raogk.org Read guidelines Choose California Scroll down to El Dorado Co. and choose Howard. Successful Searching!