Is "Zeitgeist" permanently active and needs cpu performances?

I want to use Zeitgeist together with dockbarx. So I guess Zeitgeist in this case, is only used to collect the paths to files that will be opened.

As Zeitgeist logs permanently system events, I guess Zeitgeist must always be active. Does this mean Zeitgeist uses permanently CPU resources and RAM, also if the PC is idle?

My questions are:

1.
When does Zeitgeist need CPU?
A) always. Also when the PC is idle
B) also when I move my mouse
C) also when I type in text on my keyboard
D) only when I open a program or a file
E) other

2.
When Zeitgeist needs permanently CPU (not only in case D), then...
How much CPU would it take on a Intel i5-4000
A) < 1%
B) 1.1-5%

3.
Does Zeitgeist collect data and never deletes them? Or is there a limit relating to the amount of data or time? So that when the collected data are 5 MB, it will delete the oldest data. Or for example it keeps only data for the latest week. Can we configure this?

4.
And if Zeitgeist does never delete collected data automatically, does this not slow down the system after a few months or years?

5.
How much RAM does Zeitgeist normally need to work:
A) < 1 MB
B) 2-10 MB
C) 11-100 MB
D) more than 100 MB

Would be very interested in Answers. Thank you.