I think that if your point of impact and point of aim are the same at 15 m, you are doing something wrong. At 15 m, your POI should be low, although 4 inches does seem a little much. Out of curiosity, I measured to see how high the center of my optic is compared to the center of my bore, and it is close to 3 inches. So your close range POI should never be more than 3" low (on an AR w/ EOTECH). I don't have an F2000 for comparison.
The adjustments should give you 1/2 MOA per click. So, two clicks per inch at 100 yd, four clicks per inch at 50, and 8 clicks per inch at 25.
Obviously, your bullet should be low until it reaches the range of your near-zero, say for example, 50 yards. It should then pass through zero and continue to rise to some point before it begins falling back down again to cross zero again at your far-zero, as an example 200 yards. You should select your near and far zero dependent on your cartridge's maximum point-blank range, for your given target's critical impact area, for your particluar rifle. So, if my target had a 10" diameter critical zone, I would want the highest point in the bullet's path to be 5" above my point of aim. This would ensure the bullet would travel as far as possible before going 5" below my point of aim. The combination of these two things would allow me the greatest variation in target range while still being able to hold directly on the center of my target, and not adjusting for drop, AKA maximum point-blank range.
Also, all firing for zero should be done from as stable a position as possible. I hope this was helpful.