Paolo Barbieri's illustrated book L'Inferno di Dante (see) is a gold mine: the more you examine it, the more you will come across intriguing details, in a perfect balance between high fidelity to Dante's text and personal reinterpretation. He kindly accepted to answer some questions:
Some sort of alien entity seems to be exploding out of Minos' head . . . ?
"As a matter of fact, it is a sort of crown that merges into one with Minos' head -- it might be called biomechanical, although there's nothing truly mechanical to it. My 'game' in this picture is precisely that of letting readers free to interpret it."
The Irascible: There is a strange rock on the left, like a Leviathan surfacing.
"Yeah, I applied this method wherever possible, that is, to create a sense of mystery in the very settings. Are those mere rocky formations? Or fossilised monsters? Or what?"
Lucifer is three-faced. Or, are they just masks? Other eyes, Gigerian or Lovecraftian eyes, can be seen between them.
"Ditto. I tried to add mystery to mystery -- or, to horror. Your remarks confirm that it worked."
Last but not least, Barbieri provided a 'map' to identify the demons who (pretend to) escort Dante and Virgil in Inferno 21-22. His apparently fanciful renditions are accurately based on Dante's hints: