As for how to respond to his friendly texts, ask yourself what works. When you go NC for a bit, he texts you. When you reply friendly, he backs off again right? I would stay distant for a while. Even if he is texting friendly. He just wants to test to see if you are still around. When he knows you are, he is off again. I am not saying ignore pertinent texts regarding finances, kids, etc. But simple texts that do not NEED a reply, I would just ignore. Make him start to wonder. Because right now, I am sure he does not if you are replying in friendly texts.
Just my opinion...
Me: 42 W: 32 Married 7 years together 8.5 S1: 7 S2:7 Bomb #1: 09-16-13 Recon #1: 11/13 A discovered 04-03-2014 W filed D 05-19-14 but never served me I filed D 12-02-2014 S 05-31-14 Divorced 5-19-16