USB question (pretty basic)

Factual Questions
1

Suppose I have one USB printer sitting between two non-networked computers. Can I simply plug both computers into a USB hub, and then plug the hub into the printer, or do I need some sort of switchbox? Assume that since the computers are right next to each other, the two users would be smart enough not to try and print at the same time.

How about for input devices, like scanners?

2

Do not do this. Hubs are one input, multi-output devices. They are not multi-input devices. You can cause serious damage to your computers.

Google for a USB switch (manual ones are only around $25). Networking the computers will work out better in the long rin though.