Question: I have a Ubuntu 14.04 system on which I installed the 64-bit Nvidia driver (version 343.22) from their website. Everything works fine, however whenever there is a kernel update, after reboot the screen goes blank and I have to re-run the Nvidia installer from console. Is there any way to avoid this?

Answer: 
**Move if you only need it in the target path, copy if you need it in both locations.** There's no inherent "insecurity" to `mv` or `cp`, and you'll be needlessly adding complexity (and extremely likely bugs) to your scripts if you start trying to implement your own `mv`.

For special cases there may be more suitable tools than either. For example, if you want to change owner or mode when copying there's the `install` tool which does that in one line rather than three.
It depends. In certain (usually rare) situations you should cp the file to a temporary name **on the target filesystem**, then mv it to it's final name, as the mv operation is atomic on a journaled file system. If there is any chance the application will try to read this file while you are replacing it, do this.

You specified that you are transferring the file from a different filesystem (flash drive). In this case mv is doing an implicit cp && rm. If you go back 20+ years mv didn't even support this, but there is no reason to be stuck in history.