Thanks for the tips.
What i've understood from the transform copy, it's useful to copy paste a setup pose to any animation without curves type.
But what if the pose you want to copy is different from the setup pose, because it's done in animate mode?
I'll give a more precise example of what i would love to have.
My goal is to copy and paste a specific posing on a character from an animation A, to change his start pose on some other animations B, C, D, etc... but without changing all the curves type already setted on the first frame on all the bones from animation B, C, D, etc...
here a quick preview of what i need to do at the moment on all the bones, all transformations, on all animations:
On frame 0, i've put all the key i want to copy paste values without curves type
on frame 10, the animation which i want to change start frame posing.

Cheers.