Radar Planes - 2 quick question

1) Do radar planes (defensive) need to be attached to an air unit to function, or is it sufficient to have them in stock.

2) How does one use long range radar planes to scout a neighbor?

Thank you for any assistance.

I think you only need to have the radar planes active to use them.

You have to sneak attack to use the radar planes, if they have an empire you click on it then you can click on the capitol cities and scout the defenses in the capitol. I'm not sure if there are any other ways some one more experienced in war could probably give a better answer.

If you download the "download history" spreadsheets under the general tab you can get an idea of the size and cost of their army at the time of the record, but it is not specific.