So does the PC version have a sandbox editor?

Its not present with the game. However does yet rule out it not having the editor/modding tools released later.
There are standalone cryengine3 tools being released in summer, but they are not the actual modding tools, not sure if they can be used t make mods for Crysis 2, maybe they can. I think some clarification is needed on that if they will eventually be usable with Crysis 2 to make maps, load content etc.