Dead Space 2 (DE) does NOT have DLC of any kind, which includes Collector's Edition Weapons or DLC Weapon Packs (Zealot Pack, Marshall Law Pack, etc). The availability of DLC weapons make the first half of Dead Space 2 (Xbox 360) on Hardcore much easier than Dead Space 2 (DE).
Make sure to play Dead Space - Ignition, it will reward you with 5 additional Conduit Rooms scattered throughout the first 8 Chapters that contain 5 Power Nodes, 50,000 Credits, Hacker Suit Schematic, and Hacker Contact Beam Schematic. The Hacker Suit stayed equipped from Chapter 3 through Chapter 12 and the Hacker Contact Beam was quite possibly the most important item of the game and never left my inventory. The Conduit Room items can be the difference between sucess or failure and allowed me to traverse through difficult spots rather comfortably.
If your looking for actual Gameplay tips and Strategies scroll down and read the excellent guides for Dead Space 2 - Hard to the Core (Xbox 360).