Speed painting is a misnomer, and it gets a lot of people tricked into thinking that they are good at something that they do not understand.
You need to learn the fundamentals first, the speed comes from understanding of the fundamentals. Speed painting makes people think that it is a skill they just go and learn, it sets them on the wrong path.
learn life drawing fundamentals and spend hours drawing from live models and reference.
The best way to dissect his style is to study it yourself, you need to come to your own understanding of it. But it's hard if you don't already know how to draw well. I am certainly not a good drawer either so unfortunately I can't say much besides that his style seems to resemble Japanese and American comic art somewhat, and probably uses a lot of the same technical processes.
Please don't just take my word for it though, question me, and explore.
Take the plunge.