In the previous line, Ross mentions kilos of cocaine. Tennessee is quite far away from his hometown of Miami (where cocaine can be acquired at more inexpensive prices). Thus, he tends to send his product up to TN where he can easily fetch a large profit.
An eight ball is 1/8 of an ounce, which weighs 3.5 grams. A kilo is 1,000 grams. Ross is saying that he started small selling 8 balls, a few grams of cocaine, but now sells much larger quantities, kilos.
each new cocaine dealer that establishes himself at the top of the industry brings a greater level of competition to the cocaine dealing business (bird being slang for a brick of cocaine and boss as in leader)
i hide my weapons in the attic of my mother's house and she gets them down from the attic and gives them to me when i need them - this is because if the police raid my house i don't want them to find them.
i'm mad at a person who was disrespecting or "hating on" me (a hater), because i had to shoot them and get rid of the evidence by throwing away another one of my glock brand handguns - the one i used in the crime
A reference to dealing ('flipping') cocaine of a very eminent quality, 'fishscale.' 'Flounder,' a flatfish native to the North Atlantic and areas of the east coast of North America and the Pacific Ocean, has been substituted here.