You need an Internet connection to initially download content. Once Modern Warfare Remastered has been downloaded, you do not need to be connected to the Internet to play/launch the Single Player Campaign or play Multiplayer locally. Will Call of Duty: Modern Warfare Remastered come as a separate disc?
The Chimera is a curious case in Call Of Duty: Modern Warfare 3, while it has the expected damage output of an assault rifle, its close-range optimisation is something more akin to an SMG. Whilst there are even more powerful options out there, the Chimera remains as one of the best assault rifles in Modern Warfare 3.