Some Questions for Mods abot critcal chance system

[Klausi Coolstrike]

Hi devs and mods,

i've been a great fan of critical chance system since it was buffed first time, which made it relevant for fighting.
I've made a few tests in the last days on amun (cause critical chance got buffed again) and i skilled and equipped my Marks(wo)man all about crit.
Result:
119 concentration attribute
53,28% basic critical chance
79,92% buffed critical chance (buffed with "Point shot", gives 180% crit for long bow marks)

So i thought, ok with these stats i should do more crit hits than normal hits.

My tests:
on monsters (Leader Elite Cyclops Warrior Lvl 52)

unbuffed (53,28 crit chance)
63 hormal hits
33 crictical hits -> (31,4% crit hits)

buffed (79,92 crit chance)
58 normal hits
45 critical hits -> (43,7% crit hits)

on enemy (with dual banner Conjurer lvl 50)

buffed (79,92 crit chance)
44 normal hits
33 critical hits (42,9% crit hits)

So as you see there seems to be a big gap between critical chance in character info and critical chance in a real fight.

My questions:

1) Is there a base critical evade chance that every monster and character has and if the answer is yes, it is a percentaged resist or a direct resist?
little example: 50% crit chance attacker, 10% resist defender->
percentaged: 50% - 5% = 45% crit hit (5% = 10% of 50%)
direct: 50% - 10% = 40% crit hit
Would be nice to know, because it's very unsatisfying if you skill for sth. that looks really good (nearly 80% crit chance) and you have so much hope but in reality it's not even close to that number.

2)
When I equipped my character for that insane crit chance, there happened sth. confusing to me.
I had 2 brilliant rings (15% crit chance) and 2 rings of concentration (3 on concentration attribute) and I tried out which were better for my stats.
The best result i got with 1 ring of each of them. Why is this so?
If I count with total numbers, one ring should be better than the other but it wasn't, this looks like real strange mathematics :O

Thanking you in anticipation and hope for some nice answers.

So long
Klausi