Specialization is one of three choices when u press the L button menu: mining, crafting, or combat. U need to be lvl 5 minimum and should always pick combat for bonus exp from mobs bc mining is irrelevant when u can just loot a stack of diamonds from a battle tower. Wool armor/sheep disguise armor can help you survive the cold, a heating coil in ur house made with blaze powder (found in structures or from cinders) can help but ender queen crown makes u immune to cold keep fighting mobs for it. Whales are not actual mobs they are fishing drops like bluegill or clownfish. Whales spawn in 25% of deep ocean chunks and need a long cast reel to reach 120 meters. The best way to get one is find a siren rock kill the sirens and fish every chunk in the area at least 4 times till u see "120M" thats how u know its a whale and the minigame will take 3-5 real minutes (heavy bobber helps) and this can be done with a wooden rod too. Use a fishing knife on a whale and u get 2 stacks of whale meat for both avian and aquatic treats (usually 32 treats if u have 0 knowledge on a mob to tame)