On-track radio frequencies?

I have a question for the track afficionados here. As racing spectator season approaches, I would like to purchase a scanner that allows me to listen in on track officials' communications and team driver-to-pit discussions during races. I did a search and didn't see anything pertinent, so I am wondering about the following:

Is there a standard frequency band that most of these radios operate on?

Are they encrypted?

Does each track, or each race series, tend to specify their own radio frequencies?

Thanks in advance for your help

Gio P