Gosh Hidalgo, these are terrific!!!!! I just don't know where to start. Some of them are just so full of life. Maybe inaccurate anatomically, but who cares? I would much rather look a piece of artwork that engages me than one that is anatomically accurate. Think of Picasso? Anatomically accurate?
I like the one of the horse walking away from you. I can really see it's back swinging. The tiniest addition of aa horizon line or a suggestion of a shadow or other things that suggest "place" will hellp it to exist in space. But don't go overboard.
The one cantering toward you with some color only in the background is also wonderful and I love it's unfinished look and uneven treatment. YOu allow some things to be more important and other to just kind of be suggested.
I am not as impressed with the accrylic. It is very hard to have the same lightness of the pencil, ink or charcoal works when using accrylics. I personally don't care for them except for when doing craft work (I paint birdhouses sometimes ).
Your work show defiinte talent. You might enter a contest sometime?