Is it possible now to catch a virus simply by plugging someone else's USB flash drive into a usb port?

Question

Malware

It just so happens that sometimes you need to use flash drives.

Answer 1

Yes, it's quite possible

Answer 2

Yes

Answer 3

Generally speaking, in Windows, starting from 7, autorun from removable drives is disabled initially, and in XP and Vista - in early 2011 through updates. So just by connecting a flash drive you can not get infected.
But viruses that spread through flash drives usually mask all the files and folders on them and leave shortcuts that you can run to get the virus.