its basically as if the tv had a built in android tv box, so yes, you can use it directly

A USB Hub
Cheap, simple solution

Note: avoid the very cheap ones, questionable quality

Probably would work?
For stuff like YouTube
For Netflix or other content with DRM, no idea if the screen supports DRM protected content

Also, you should probably power it from a cigarette/accessory socket car charger, since the USB ports built into car players are usually only expected to power a low power USB drive, not a tv stick