My guitar's neck is not straight with the body. It bends behind the body if you know what i mean.
It's normal. A les paul, or les paul copy's neck is at an angle to the body.
Whether the neck itself is straight or not is a separate matter.
I'm outside now, but if I have time I'll take a photo of my les paul copy for you to reference.
And when i lift up the guitar from the neck, it creates a sound like when you press down on a whammy bar.
Okay, from what you are saying, I gather that you are bending the neck. Otherwise the pitch would not change (the whammy bar reference).
Please do not lift you guitar by the neck in such a way that it puts stress on it such that it bends.
Unless of course you are seeking to destroy it.
Hope this helps.