Ravens are a one way communication. She would send the raven and the answer would be the KOV showing up or not showing up. Same as when Jon was talking to Lord Glover, he said he sent ravens to the Manderleys but it's not a two way communication as far as I know. But then again, Raven science hasn't been covered in the show lol
I'm pretty sure ravens can fly in a wide variety of directions.
I'm with Angie on this point. I think the way the writers handled the Sansa-KOV plot point was weak. After watching the Battle of the Bastards episode, I remarked to my son that if they don't have some serious tension between Jon and Sansa after her sandbaggery it would be pretty ridiculous. And there certainly wasn't a whole lot of acrimony, just Jon saying, "We need to trust each other." Ugh.
This particular plot line hasn't ruined the show. It doesn't completely invalidate what is a damn good watch overall. But it wasn't good writing in my opinion. They could have done much better. And if they wanted to go with the Sansa felt she needed to keep it a secret angle, there should be way more tension between Jon and Sansa beyond just a "Whatevs, we've got to stick together sis" throwaway line. Just my opinion of course.