1. They most likely will, unless characters decide not to, in which case the scientists can help with that. (This would be for characters afraid of changing the future with the knowledge they gained here, since that is a risk.)

2. Romaeus isn't all-powerful and it's supposed to be a two-person thing, but since Kari can dimension-hop anyway, she might be able to take a couple extra? The chance of success would decrease with each additional person, though, so it's at-your-own-risk.