Star Wars: Obi-Wan Kenobi

[Graystoke]

I guess this might be a stupid question but here it goes.
I was under the impression from A New Hope that Leia didn't really know Obi-Wan other then through name. How are they going to fix this? Or am I erroneous?

And to build on that if Obi-Wan is going to put himself in grave danger rescuing Leia not once, but twice, isn't that going to send off signals to Darth Vader the importance of Leia?
Fill me in folks.

I am enjoying this show. Episode 4 having Obi-Wan rediscover some of his Jedi skills was cool.