Aircraft and Artillery Intensity

[OldGamer]

I'm still not clear on what the numbers for artillery mean. For example, does 2.4 mean the delay is from two turns to 4 turns? 3.5 is from three to five turns. For the both examples, would 1/3 of the available artillery fire in each turn?

Another question about artillery concerns it accuracy. If the spotter who called in the artillery has a line of sight to the chosen target hexes, is the accuracy of the artillery better?

Thanks again for your help.