Okay I got you some fun old info well first things first, Alcohol tolerance should be pretty easy for something as massive as 8-13ft, also considering it is of Asian descent then its tolerance of Alcohol is even more increased on account that Asians and Europeans have the highest alcohol tolerance of any other race, but if you want even more then you are going to need more of the special enzymes for digesting alcohol and bigger livers. Humans are already omnivores so no change is needed there.
Next is the size, 8ft is pushing it for something with a relatively human shape and at 13ft survival is 0. but don't worry all hope is not lost because all you need to increase that survival chance is to shift the organ sizes and body shape. So taking tips from our real life giants the major organs that need this is the liver, lungs, heart, and stomach. Now lets go to everybody's favorite subject, mitochondria density, yes the mitochondria will be needing to decrease the density of mitochondria per cell so the body does overheat, causing the proteins to unwind and the body turns into a pile of mush. Also considering they will live in hot climates(well hell is listed as on =e of their environments so I'm guessing its hot) then they will need to take a page out of the elephants survival as a giant guide, and get the most surface area it can buy having wrinkly skin. Now for the actual body shape, it will need pillar like legs(like an elephant), a wide frame, proportionally shorter arms, and probably smaller brains because the energy needed to maintain such a huge stature.
Okay last but not least we go to the skin color behavior correlation thingy, and while yes their is a disease that turns you blue(Methemoglobinemia) its not the best thing to base a species on. So what I propose is their skin color, and behavior actually comes from their environment and what they eat. this has actually happened to some African Tribe(Tuareg) and could be used to explained the behavior of the diffrent colors by saying its from culture or just that the red ones have a constant rash that causes them to be aggressive all the time.
Hope the answer helps! (;