Those are some pretty bold statements you got there, and you're ignoring a lot of other key aspects of their relationship.
I agree with Loligo that Rachel is more protective than straight-out domineering--she's always frustrated that Tobias doesn't become permanently human which would effectively put him out of the fight, but if she wanted to actually control him she'd push for it more. She could have made him stay in his human morph for over 2 hours in #33, but she helped him escape in the end. And this follows #32 which makes it clear that Rachel isn't just a berserk, dominant ****, and the end of that book is the one thing I absolutely love about it, when they go off together. "The two of you and the two of me." There's more to Rachel than the bloodthirsty warrior, and there's also more to Tobias than the emo wimp.
I do think she finds his predator side attractive on a certain level, but more than that, she acknowledges his strength. Just the fact that he can live as a hawk at all makes him kind of impressive. Plus, he pushes aside his own fears just so he can look after her. He offers to go on the dangerous AMR mission. He doesn't back out of the fight. Rachel may want to protect him, but she also admires him. She trusts him. He's the one she confides in and vice-versa. Even if there are other things at work, I don't think you can simply write off the fact that they do actually care for each other.
On the Marco/Rachel side of things, I do agree that they're compatible and I love their scenes, whether they're bickering or Rachel is talking to him after an episode with his mom (the best part is that Rachel doesn't try to be nice to him like Cassie does, and Marco responds to Rachel better because of it). I like that they date in MM4, but I disagree that their dating and Tobias not being a hawk means Rachel/Tobias would never work. They didn't really know each other in MM4 so you can't hold that against them.