Arrow IV was mech mounted artillery. And I do think AMS specified missile types, so no, not effective I don't think, and at it's effective range I wouldn't think blowing the Arrow would be a great plan anyway.
Depends. If it counts as a missile type system for the hard points then yes you could, the C3 would just come with it loaded. I'm sort of hoping it gets a special hard point type but then again similar MW4 systems weren't incredibly common either.