There are probably some questions on universe 2 that might be to confusing for the normal Kingdom Hearts fan to handle. So here are the answers to most of the questions which I doubt you had.
Organization Negative 13's PlanThe Negative 13 is a group of Nobodies that are all from different worlds of the second Universe but only 2 are from Sora's Universe. Xansem (-1) who is Xehanort's Second Nobody and Xurik (-12) who is Riku's Nobody. They are the opposite of Organization XIII but are still evil infact none of the members of the Organization were truly evil (as answered down below). They are stealing people's hearts to make their Kingdom Hearts complete so they can exist but that's not all. After that they will put their revenge into work by destroying the CN Realm which is the Universe's Heart. In thoery would destroy everything in that universe. Then take over the firsy universe.
Evalights are beings made by Dark Light. If someone who is trully evil turns into a heartless an evalight will be made. There is only one person who is that evil and that is Xehanort. Only one was made but they're like a disease. If one touches a Heartless, Nobody, or even an Unversed then the one who is touched will be turned into on to spread it. They can only be seen in The Intersection.
Organization XIII Good?Organization XIII was good an wasn't trying to hurt anyone but their darkness inside their bodies and with no hearts made them do all of that stuff. But Xemnas...In The Intersection Sora was worried about Xemnas because when they mentioned Therac. He had a smirk on his face.
Omnitrix and Keyblade Connections
Both the Omnitrix and the Keyblade have only 2 simalarities
1. both used to bring all of the beings of the universe closer to each other
2. Both from seperate worlds
In Bellwood Asmeth told Ben and Sora the connections after warning Ben of the stuff that could happen if he hacked the Omnitrix
Dagin and Sora
Truly Dagin knew what Sora could do with a keyblade before Sora was even born. So when he was born Dagin used his keyblade to give Sora the ability to control it so he can prove that he is the keyblade master and set things right
Negative 13 SomebodiesXansem - Xehanort (Ansem)
Shaxel - Leash
Luxem - Leum
Arx - Ra
Iax - Ia/Ilizabeth
Ax - A
Zixard - Driza
Gexini - Nigie
Fixura - Furai
Controx - Tonroc
Xremurd - Murder
Mexa - A.E.M.