"…the breathing of a massive creature[.] Another red hue comes from the core of the pile…" (separate into two sentences)
"…another red hue comes from the core of the pile[;] it looks like the covered entrance of Hell." (add a semicolon; these are your best friend)
"The bodies [forming] this pile lie motionless, only [shaken] and lifted by the breathing of the mound[.] They are made with incredible[,] impossible details, the most detailed, even if only 6,37 cm (2.51 inches) a couple of inches tall, has distinct hair that can only be seen through a microscope." (punctuation, overexplaining, yadda yadda)
"…so, in rage as he sees he cannot paint emptiness, he punches the canvas, punches a hole [in the canvas, a hole] through this maddening task." (rewording)
"Then, as he removes his hand, he sees it[:] the emptiness, emptiness, not of will, [not]even of emotions[;] he filled the hole in the canvas with rage, but the canvas itself, the support of his rage, his anger, his painting[,] doesn’t exist anymore" (punctuation, redundancy)
"…his painting, doesn’t exist anymore[;] he made art with no support, and as he realizes this, he sees the art in all it’s glory[;] he basks in the light of an art which he cannot see, which cannot be seen, heard, tasted, touched, [nor] smelled but can only be felt,can only be [and] lived." (even more semicolon)
"… a dread washes over him[.] He fears, and, precariously, he takes the knife that had been laying on his table, observes the 25,025 cm (9.58 inches) blade, sees the fine craftsmanship of the hand-made edge, sees the slight curve at the tip of the blade where the artisan was tired, sees every detail of the wood, every slight dent, and plants the blade in the heart of his art, dying in the process." (more of the same)
"This painting, with the punch-sized hole in the down-left corner of the 3.657 m (12 feet) wide, 5.884 m (19.16 feet) long canvas, with a pile of human bodies and a mad, stabbed shark, at the center, both entirely inscribed in a 27.64 cm (10.88 inches) wide and 43.82 cm (26.86 inches) long rectangle, this painting was sold for 978 466 million euros on the 7th of October 1989, putting the man who bought it in debt for 8 generations. And The shark is [appears] so goofy it could barely be considered art." (you get the idea)
"The painting was broken in half in 1996, when the man, who was 57 [buyer] accidentally ran it over with a tractor as he was drunk [in a drunken stupor]." (wording)
(other notes: unless the measurements are a narrative detail, i'd do away with them.)
