A llama is a tamable neutral mob seen in Minecraft. There are unique characteristics associated with llamas, such as their behavior of spitting. Despite being neutral, if a player or mob attacks one, it spits at the attacker once to deal 1hp damage. If it's a tamed llama belonging to a wandering trader, it will spit at the mob or player which attacks the wanderer. Sometimes, their spit can miss their target and hit another llama, starting a fight within a group of llamas. Dying from llama spit still shows the death message "<player> was slain by trader llama or llama“.
If a player attacks a llama or its owner, it turns hostile and starts spitting. Each spit entity that hits the players deals damage of 1 hp. They can also accidentally damage other llamas, which can start a fight within their group. Llamas are particularly defensive when they face wolves and call spit without provocation. However, they won't attack tamed wolves.
A. Yes, although tamed llamas do not spit at mobs that attack their owner, it spits at any mob that attacks the llama.
A. They won't stop unless they die, lose their target if you reload the world, or are given a new target.