To answer your first question, yes, I am the person who posted the pictures on Find a Grave (though, I do not control the actual memorials on the site yet so I cannot add more information to them). As to your second question, I do not have his service record or pension information as such, but I did find an application by Matilda after his death to continue receiving the pension benefits as his widow. I also have a little information from when he signed up for the Civil War.
Thank you also for the information about his middle name. As I said in my original post, I don't think anyone ever told me what his middle name was. Every reference that I had found always showed only the middle initial.
I do know more than what I originaly posted about his life, but I did not want to get anyone who might look at this bogged down with too many details. I knew the dates of his birth and death (and the children that he had) from the tombstone and an obituary that I found in the local paper of the period. Unfortunately, the obituary gave no details of his life before he came to Indiana (which was sometime in the 1850s I am guessing). I found his marriage record on Ancestry.com when I had an account in the past. I also know from census info. and family stories that both he and Matilda lived in northern Brown County, Indiana before their marriage. Her family did not apparently approve of the match (perhaps because she was too young or he did not seem to have suitable means at the time) so she climbed out her window one night and they eloped on horseback to next door Morgan County to be married. Interestingly, as a side note, I did find one source claiming that Matilda Haskett was born in Goshen Township in Belmont County, Ohio, but again I do not know that he knew her or her family before he moved to Indiana. He did serve in the Civil War, but in 1862 in Louisville he apparently suffered from a hernia and he was used for light duties as a signalman or in the reserves in some capacity for the rest of his service. Before the war, I found in the 1860 census that he was living with another family in Brown County. I know that it is him because I found a reference to him signing up for the 82nd Ind. Inf. from the same small, rural location several months later. This is why I assumed that he moved to Indiana alone and any surviving family was probably still in Ohio at the time. Overall, I know quite a bit about his time in Indiana, but I know pretty much nothing about his time in Ohio.
As I said before, he claimed to be born in Barnesville, Ohio; though, from what I can tell, it does not look like there were many McDonalds in the Belmont County area at the time. I assumed that either the family moved or through some unfortunate circumstance such as his parents' deaths he was forced to move, perhaps to live with another family. However, I have been doing some research online and according to Find a Grave there appears to be quite a few Mcdonalds buried in Muskingum County. Perhaps he was born in Barnesville and the family moved a few miles over to Muskingum County. From what I could tell, there were several men in Muskingum County old enough and named Mcdonald who claimed in the census to be from Pennsylvania so several of these might be potential candidates to be James' father. I have not seen anything to confirm a potential mother from Scotland however.
I am mainly trying to find more information about him because he is more or less like a brickwall in my research down the McDonald line. Without the names of his parents, there is no way for me to move any further down the line. Given that it appears likely that his family might have been one of the McDonalds in Muskingum County, perhaps I should try posting in the Muskingum County sub-forum on here.