Unfortunately there isn’t anything that can be done about the first two points. Dependencies between events can’t be imported/exported via csv file in either version, or titles of Links. We do plan to add the ability to edit links so in the future you will be able to edit the title.
In regards to parent-child relations, these should be able to be imported/exported. When you are importing into version 3, what option are you selecting for the column Event ID from the version 2 export? If you choose Internal ID, and then you choose the Parent column to import to Parent, this should keep the parent-child relationships (as when you exported from version 2 it should have saved each events parent’s id in the Parent column).