I found a Government Land Office record for John YULE which indicates he acquired a parcel of land in dodge county in September 1848. You can see the record by visiting the Bureau of Land Management site and searching their land records. Here's the link: http://www.glorecords.blm.gov/http://www.glorecords.blm.gov/
Click on the "Search Land Patents" button along the top of the page then follow the prompts, which will ask you for a state and a name.
I haven't been able to track down their death information either, so I guess we're in the same bat there. I am in contact with someone who promises to send me a scanned photo of John and wife Elizabeth Keller. I'd be happy to pass along if that pans out.