The launcher will ask for your MW3 folder path. Typically:
C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Modern Warfare 3
Yes. Even on the final official patch (1.9.461), you can enable the developer console—though not through the simple ~ key press anymore. You must use one of the following verified methods. The launcher will ask for your MW3 folder path
Short answer: No — not in the official, fully patched version of MW3 (2011) multiplayer or Spec Ops. The launcher will ask for your MW3 folder path