Probably the single biggest pieces of information released. This clears up any ambiguity. Some Jedi have now officially survived Order 66.
Yoda's conversation with Obi Wan and the whole "there is another" and then telling Luke "there's another skywalker" never made sense and now there is definitely wiggle room there.
I don't think so. "another hope" doesn't just mean any jedi. They needed Luke or Leia for this particular thing in order to bring Vader back to the light. Just any ole jedi wasn't going to cut it.
Unless Obi Wan developed Alzheimers when he became a force ghost he already knew about Leia.
Regardless if Yoda COULD have meant other Jedi or not, Obiwan still would have known about Leia.
Unless the point of the exchange between Obi Wan and Yoda was as simple as Obi Wan didn't consider Leia an alternative and Yoda did, which would make it a terribly mundane conversation, then it seems to me the greater possibility is that Obi Wan thought the only option was Luke and Yoda corrected him otherwise.