Yes she does dies... so ZX wants to kill Jing. ZX goes to Hou and entices him to do it and he does. Hou had Yi Yang poison their own son to setup a trap for Jing. Jing sees Zhen like his own son so he cares alot for Zhen's wellbeing. Jing was suspicious of the situation so he brought extra guards just incase something goes wrong, plus this happens a month b4 his wedding day and he wants to make sure he makes it there. ZX helped Hou take out all of the guards while Hou battles Jing. Since Jing agreed to the battle he wanted to pick where they battle take place and he picked somewhere closed to the river. Hou conjured a tiger while Jing conjured a 9 tailed fox. Hou pounced on the fox plucks the fox's tail one by one, when Hou was about to give the final blow Yi Yang shot an arrow at his chest. Yi Yang came up to him, used one arm and wrapped around his waist and held an arrow on the other. She used her remaining power to push the arrow forward until it pierced fully through Hou's heart and into her heart. Hou used his remaining power and kicked Jing as hard as he could and Jing flew into the river. Only reason Yi Yang agreed to set up the trap was to kill Hou. Jing did not die he was rescued by a mermaid couple (it was really Xiang Liu) but he was greatly injured, he was unconscious for 7 years.
FL doesn't get her powers back. It wasn’t sealed it was forcibly stripped from her. Hey her and Jing are the same at the end!
I don't understand your last question.