The secret is nobody can tell. There are probably like 5 people playing with that band who have the equipment to receive it and as long as you don't do anything too obvious within literal line of sight of those 5 (very old) dudes the world is your oyster.

Yes it is. But there are many things it can still be used for. In Holland for example they use microwave connections to create a backbone network to do things like repeater linking and to distribute amateur TV without using the internet like most current repeaters do.

See some of their applications here: https://hamnet.nl/toepassingen/ (Sorry, it's in Dutch but you can use a translator :)

Only if it's used to obscure the meaning of a message.

You can encrypt passcodes and remote control commands for sattelites and other radio control codes for various craft or devices. You can also still use message authentication codes for integrity of plaintext messages.

Telemetry is fair game for encryption IIRC as well.