Peg,
I checked the 1870 census on Ancestry.com, which is fully indexed so it should list him even if he is not head of household. I didn't have any luck finding him in Tippecanoe Co., IN at that time. But, I suggest you visit a library which has a subscription to Ancestry.com (most do) and do some creative searches of your own, substituting various spellings that you have encountered or tried in your previous research.
Also, in regard to finding a death certificate for Edward from 1898, it's not very likely. Indiana did not require health departments to record deaths at that time. In those days, you could bury Uncle Ed in the backyard if you so desired. However, you might still find him in a local church register.
William Taber, Indianapolis (formerly Lafayette)