your 20 questions is very confusing to me too

welcome by the way.
Please highlight the website which said that DX lenses mount on DX body there will be no crop factor....
If you are not a seasoned film (35mm) SLR user, chances are you won't understand what all this 'crop factor' is about.
You mount the lens on the camera, look thru the viewfinder and all seems ok.
So in that sense, the 'crop factor' is not so critical to you.
To explain this crop factor in one post is kinda tiring. Besides, this topic has been explained to death numerous times over clubsnap.
Can try Googling for 'crop factor'.
The background is that the sensor on the D90 is smaller than the usual 35mm film, hence there is a 'cropping' of the image compared with the film SLR.
Why do you think that metering would cause blurness? Sounds to me like you just hantam all these new terms in without really understanding what they mean. Go slow... learn them one by one, otherwise you'll just confuse yourself totally.