1) I installed OwnCloud (had to upgrade to VPS), and tried DO and it was horrifically slow. Local storage is much faster. Since I'm on VPS, I doubt there's much concern about abusing the "Unlimited" storage policy.
2) I'm as excited as the next person with shiny new products, such as NextCloud (fork of OwnCloud), but when one tries to download a client and gets a "File Not Found" error, it's time to look for something else. Followed link from https://docs.nextcloud.org/server/9/user_manual/
3) I don't know what the issue is with Google Drive, but if you're in that arena, why not try Dropbox? Unless the 2GB limit is an issue.
4) If your unskilled user wants to drop off a bid of proposal, why not email it? And if a rancher wants to read a report, host it on Dropbox and send him the link (again, I don't know why Google Drive is having trouble with this).