1.) Use arrays for dialogues , C2 never supplied sprites for dialogues , but you can always customize the text boxes with CSS !
2.) Never made a mobile game , so I can't answer you for that
3.) You can , you just need to be sure that the objects referred in the events and all their settings are the same in the two projects or C2 might crash on you ... I'm sure libraries are on Ashley's list
Cheers ...