ESX 5.x USB Questions

Hi

I am currently new to a company and we have an ESX 5.x estate. I believe we boot most of our ESX hosts from USB, which I've not done elsewhere before and I have a few questions:

1. Where in vSphere Client can I see whether a host has booted from USB?

2. Can the USB be used for any hardware if I transport it, or is it bound to that make/model?

3. I assume you can't use VUM for host updates if you boot from USB?

4. Can I create the USBs on my PC before shipping them off to the server? (Complete with IP info, etc)?

Thanks