You don't need to do anything when activating Tekkai and in this chapter we learned that WsW can do Tekkai while moving like Jabra.
Wrong, there is no focus on Jinbei's arm. We see Jinbei, who just blocked and bounced back an attack, so he still remained in that pose, therefore he had the arm in front of his face.
That was a draw error, he used Haki in the previous page.
https://scans-hot.leanbox.us/manga/One-Piece/1017-014.png
He only said the names of the first three, but not the fourht.
The fourth was said by Jinbei himself for us readers to understand that he just recongnized the techniques which are only used by government secret agents and concluded that WsW was a former agent since he heard about one escaping some time ago.
He is not talking about him at all, all the context is about WsW, Rokushiki and the secret agents.
The same "SFX" argument is a joke lmao. With that, Sanji has Conqueror Haki.
The lightning argument, another joke. In this same chapter we just had lightning effects when Jinbei broke his wrist but we didnt have when they clashed Haki against Haki.