I think it's more likely that Lea, Mab, and yes, Rashid, all believed that Molly had the potential (if they're anything like the Mothers, they see multiple potential futures) to become, in some way, important to the war against the Outsiders. Rashid saw that the futures in which Harry did not get involved in Molly's situation are ones in which she is dead (likely executed by the Council) or corrupted and playing for the wrong team.
In short, I do believe that Rashid knows how important Molly would become, but not necessarily how she would be important. He just saw darker futures ahead if she were dead and/or corrupted, and eventually the White Council would have found her and executed her for using black magic if Harry wasn't willing to take responsibility for her. That's why he tipped Harry off.
Rashid and Mab definitely do have to have some kind of reasonable working relationship. I think that the regular fetches were just doing their thing—showing up at a beacon that was close to them symbolically (Molly, who happened to be at SplatterCon!!!) and enjoying some bonus meals. Mab figured out that Molly was in danger eventually, and sent Eldest Fetch to bring her to Arctis Tor both for an examination to make sure she was clear of Nemesis infection, and to keep her safe, but placed him under strict orders to act in all ways like a normal Fetch. (Personally, I don't believe that Eldest Fetch would bother doing anything like what the other fetches were doing; he was way too high up, too powerful, to be wasting his time on that nonsense without orders).
...Or something. I don't know, I'm tired.
