Yea... that's a problem with most cinematic universes. There's simply so much of story, that you cannot start in the middle. I'm not really sure what you mean by "dead space" between lines. The conversations kinda felt natural to me....

I don't know why people didn't like Dawson's acting. I kinda felt her portrayal of Ahsoka as very faithful continuation of her portrayal in Rebels. She has been through A LOT. I personally have seen people who have had a hard time in life being withdrawn, devoid of emotion and very stoic. In fact, this portrayal of her makes her very believable for me. She's not a happy teenager anymore. She's a middle aged, lonely individual who has a lot of responsibility on her back. She has no family. Rather, she just has a few "accomplices". Plus, she is worried about an impending invasion from one of the most feared and effective imperial Generals.

Why is he more important than stopping a war?

He is important, as he could very well be a part of this war. He is an extremely powerful Jedi Knight. Could he have joined Thrawn? Him not contacting the Rebels back probably means that he is either dead, or has joined Thrawn. This is very dangerous for obvious reasons.