You aren't capable of seeing his chakra being inserted into you or this chakra that you claimed to see around him with the Sharingan, you can't see the chakra traveling into you in a noticable manner in case of genjutsu techniques specifically and this is even an eye technique genjutsu it's even harder to identify, Lilliana, Scorps and Scary Yamato all agree to this, because i fallen into the same mistake myself lol xd
The reasoning for the genjutsu i don't agree with honestly, why would it be suspicious when you stab him? that was your original plan, to me this seems a bit like you saw that he performed a genjutsu in his post and decided to take that to your advantage without making it a reality, you are a Sharingan user, Sharingan users are capable of knowing that they are under a genjutsu with 2 things, one is following the visual "false" changes, the Sharingan is able to identify, and the second one perceiving your own chakra, which would be disrupted and flowing irregularly around your body, which would make you positive that you are inside a genjutsu, you had an advantage to that as well, because when you move your hand forward to stab him, your arm would be in your line of sight, so you would be able to see your chakra's irregularity right there, it's a technicality but it stands, so i'll leave that up to Darui whether he can roll with it or not lol, however the timing wouldn't be that off like you guys say, in order for the genjutsu to play out the way you wanted it to, you have to keep manipulating your chakra in a way that keeps him inside the genjutsu, it doesn't unfold on it's own lol, so as long as he is seeing occuring changes within the genjutsu it means that you are bound to use your chakra in order to change how his senses experience the illusion, that's why genjutsus require such delicate and precise chakra control.
As for the Kai, yes it requires a handseal to be performed, handseal or clapping your hands together in case of Naruto, it was shown to be performed by both, but never has been seen that Kai is performed without a hand gesture, that's why it can't guard against paralysis genjutsu, its also mentioned in the technique's description that it can't get you out of paralysis genjutsus, and that genjutsu Darui used the "Eye Technique: Bound By Soul Technique" is a paralysis genjutsu, that escape you made was invalid, biting your tongue off wouldn't cause you to die instantly, it will take sometime for you to die, it will however decrease your mental ability, your reactions, speed and overall usage of techniques, we really should make a rule about this lol.