Edgehill Theological College in Belfast may have details of his career in the Methodist church. Robin Rainey is in charge of the historical section. He may be able to help you.
http://www.edgehillcollege.org
According to the PRONI website, there were two Methodist chapels in Clones. The Primitive Wesleyans have records from 1872 onwards, and the Wesleyans have baptisms from 1839 and marriages from 1872. There are copies of the above records in PRONI (the public record office) in Belfast. They are not on-line, and so a personal visit is required. Prior to the above dates, the members of those churches are likely to have used the Church of Ireland for baptisms and marriages. Clones COI records start in 1682. (Copies in PRONI). Of course if Robert was a Minister, he may well have moved around a lot, and so might not originate there.
A marriage in 1826 almost certainly won’t have any additional information other than the couples names, the date and their 2 witnesses.
The informant on a death certificate can be anyone present at death, not always next of kin. Sometimes neighbours or hospital officials register the death. Or it might be a daughter.