In the future, what should I do about Windows updates? Should I be concerned?
Not concerned at all. You can do "system restore now" to go back in time (only for settings and system files). Why was system restore not enabled?
Windows updates modifies system files and settings. No idea why your userprofile was corrected all of sudden. It wasn't related to the updates I assume.
We didn't rollback the patches anyway.
In a few weeks you can delete in C:\users the folders (and all inside it): oldusername . There's also a temp for your username.... deleet that as well