1- Power from the world ''Existence'' doesn't work in the real world ( it was the T's who added magic in his world but the real world has no magic) which is one of the reasons Alex couldn't use his God power at first in Milker and the reason Butterfly kidnapped Mirall in Milker in order to push Alex into despair and reactivate his power again.
2- Yes CC in ''Existence'' is very different which has to do with the rules of the T's world. Instead of the player, CC is obsessed with Alex in this game. The future game that will take place between ''Existence'' and ''Milker'' will address this alongside ''Eva'' transformation back to ''Carmine''.
3- Alex's power didn't charge at all, it was another thing that intervened.
4- No it's not a plot hole. ''Carmine'' was ''Eva'' in ''Existence'' but once they escaped ''Existence''( in the future game I haven't uploaded yet) . Alex went into the timeline of ''Milker'' to find Mirall while Carmine went back to her timeline.
Then in ''Milker2'' ( a game I'm still working on) Carmine comes to the Milker timeline then once that game concludes everyone returns to their timeline and Alex goes to the ''Devotion'' timeline to hunt ''Isaac''.
This is where Alex tells Carmine to wait for him, Carmine accepted on the condition that Ellie keeps updating her on what's happening.
Meanwhile ''Goodbye Time traveler MC'' never told his Carmine about the Null's world.
5- You shouldn't feel bad about Hassan, he has his own ''spin-off'' game in the making. Although I'm not sure if I should finish it because it's too ridiculous and more of a comedy eroge than a serious game that contrasts with the series' seriousness so far.