DarkGravityWave3

[Mr. Lee]

From white paper:

DarkGravityWave uses multiple exponential moving averages and a simple moving average to smoothly adjust the difficulty. This implementation resolves possible exploits in KimotoGravityWell by limiting the difficulty retargeting to 3 times the 14 period EMA difficulty average.

However, looking into the implementation I see that DarkGravityWave3 is very simple, I don't see there any "multiple exponential moving averages". It just takes average difficulty of last 24 blocks, target timespan, actual timespan and calculates new target based on these.
I have several questions:
1. Where are these "exponential moving averages"?
2. Why last block is counted twice while computing average difficulty of last 24 blocks?
3. Isn't 24 blocks too small interval? It is one hour and in Bitcoin (I don't know about Darkcoin) there is big tolerance to nTime in newly mined blocks, it can be set to something like half an hour in the future or in the past if I remember correctly. Doesn't it allow miners to manipulate difficulty?