Kali VM Ware iso vs Kali ISO and USB Question

First, let me apologize for only using Linux for one day--ever. I don't know what got with me, but I have a very strong desire to use Linux when I can, and migrate from Windows to Linux unless it's necessary to use Windows. Anyway, I've loaded a live USB Ubuntu and Mint and messed around with them, and I am very impressed. But, that's the extent of my Linux experience, sad to say. I've used the MS OS since the DOS days, so I am comfortable with command like use.

Anyway, to my questions. They pertain to running Kali on a Windows machine through a virtual machine.

What I want to do: Run Kali from my Win 8 Pro install using VM.

(1) What is the difference between the Kali ISO and the Kali ISO VM Ware ISO version?

(2) I'd like the VM version of Kali to be persistent. Can the persistent information reside on a USB drive, and would 16GB be enough?

Thanks and please forgive my Linux ignorance.

1. Kali ISO is Live CD, you can boot the system from CD or can Install it on the system. The VMWare is ready installed image, you just need to open it and have persistent system.
2. Yup it can persist on a USB. Default install of Kali takes 6.4GB, plus to have some space to work with. Anything >=10GB should be enough.

You should check this All About Kali Linux