I checked to see if my Firefox install had vanished and it has not. I scanned through my other installed apps and can't find anything missing. I also checked the photos and files from internal storage and my external SD card. Everything is present.
Unfortunately, updates seem to cause issues for some people and not others. I find the situation where people report randomly losing user-installed apps, pictures, etc, to be highly perplexing. I completely believe this is occurring but there's just no explanation and I have yet to see anyone come up with one.
Hopefully, you are able to recover the lost images and such. While I never want it to happen I always keep my data synced through Google, Verizon's backup service, etc. Redundancy isn't a bad thing but the fact is we don't want to ever have to need to worry about it.
Note: Some apps can/may be removed during an update at the discretion of Verizon and/or Samsung when it is one that was sponsored/bundled when you purchased your phone. Samsung discontinued their Milk Music service, for instance.