Road surface and consequently traction can vary (for example, gravel). It's important to stay well within margin. Once you lose traction at speed, it can be hard to get it back. TL;DR take it to the track, where the road surface is well maintained.
Technically yes but on any given track day there can still be gravel, weeds, rubber, bits of material from car body kits/aero, and even various liquids that have leaked.
If you do hit gravel/oil, tracks at least have runoff areas or soft barriers, and no oncoming traffic or cliffs to worry about.
Every track day I've attended required the cars to have been inspected for leaks and loose components. And they were quick to clean up any debris or oil.
Not that tracking cars is the safest hobby, but if someone is gonna drive like that regardless its far safer at a track than on public roads.