Oathed: is there a fanmade patch or bugfix to reliably run this on Windows 10 without serious issues?
There aren't any fan patches. However, in general it should run fine in Win 10; you could run into issues, but considering the age of the game it isn't particularly buggy.
The digital version does have one consistent known issue that I can think of, which can cause a crash loading late game saves, triggered by completing a quest from a merchant near the end. This can be avoided by not bringing him the amulet he wants, and is fixable if the quest is completed.
I don't recall missing saves being an issue. However, periodic named saves are always a good idea, and you can zip or otherwise backup the saves in the 'savegames' folder in the install folder (if you have a lot of saves,
7-zip's .7z format can achieve much better compression than .zip).