Military Units (Fearless Blue)

Ive tried to read the documentation and I just wanted to clarify this,
If I buy an interceptor and place it in my war stocks but do not deploy that interceptor in a defense wing does it:
A. count the same amount toward my defense index as a deployed interceptor and
B. require the same amount in military spending each month?
Thanks
HS

Yes and yes, assuming you don't deactivate it.

In the event of an attack, if the unit is active does it participate in the defense of the country? Or does a Defense Wing need to be created for defenses?

If you just own a bunch if interceptors in your country stock, they won't help fight off any attacks (except maybe against the airport they're stocked in? Not sure on that one). You have to put them into a defense wing for them to actively respond.

Land defense units don't respond automatically at this point, but the garrisons will

Sometimes when I try to place units in a garrison it says I have negative units available even though my stock says I have thousands available and not deployed. Anyone else come across this?

There is a slight bug there... if you go to war, defensive forces, plan defense and hit recall all troops it should clear up