Explicit Supply/Air Units/Artillery Questions

[Compass Rose]

Explicit Supply: I am wanting to start playing my PzC games using Explicit Supply. I have zero experience in using it. I am aware that even if I select the optional rule, it may not be used if the scenario was not designed to use it. Is there a "trick" to knowing ahead of time whether a scenario uses the rule of not? Does anyone know of any small scenarios that use the rule (So I can practice with it)?

Air Units: If air units are available during a turn, and you don't use them, are they automatically available on your next turn, unless the weather is bad, or do you loose them?

Artillery: If at the start of a turn you have available artillery and you do not use them, will the same units automatically be available for the next turn, or could some of them become unavailable?

Thanks