1.Why the particle, which falls in to a black hole might have negative (dark) energy and repulsive gravitational force?
Why not quite the contrary?
No one has ever suggested that dark energy comes in the form of particles.
Dark energy is some sort tenuous quality of the current universe.
When, and if, dark energy becomes much more dense
it might be interesting to speculate about it's effect on black holes.
Comet Hartley 2
2. How big is a black hole radius for a proton? quark?
has a black hole Schwarzschild radius of about half a proton radius.
A flea's egg has a black hole Schwarzschild radius of about a Planck length
It makes no sense to talk about black hole Schwarzschild radii that are smaller than that.