Re: samsung knox for private/business use
As I understand it just from looking around on the phone after the 4.3 update, that update installed certain Knox components to the phone, but did not actually install the main Knox program. In the app tray there is now a Knox shortcut (its icon has a little curving arrow at the bottom left). Tapping that takes you to an information screen with an Install button.
Don't tap that button! I believe that it is what would put the main Knox program on your phone. My advice (just from having done this myself, and decided not to install Knox) would be to read the information on that screen and look online at what Knox users are experiencing, and be certain whether or not you want to do this to your phone.
Based on what I read on that screen, it sounds like Knox works similarly to a "virtual machine" on a Windows computer. The information screen indicates that inside the "Samsung KNOX container" you're in "another private mobile," and in that space "there may be restrictions on moving data into and out of [the] container and some applications may have their features restricted."
I have yet to read of any actual benefits from Knox. Of course, all I'm reading are gripes on these forums.
I'd also recommend looking at this thread on the Verizon S4 user forum:
https://community.verizonwireless.com/thread/809366, particularly the detailed experience reported by LadyRelm2.