Remapping the key bindings in Bioshock 2 for the PC renders several functions unmapped, with no way to reconcile through the GUI. Below are some of the fixes I've found. You must edit your Bioshock "User.ini" file (back it up first of course). The location of this file differs based on your version of Windows; for Windows Vista and Windows 7 it's in hidden folder "C:\Users\YourUsernameHere\AppData\Roaming\Bioshock 2".
If you can't hack (remote hack dart), in section [HackPrototype] (83% of the way down the file, at line 15467 for me) type "HackAction" after the key of your choice. Example:
[HackPrototype]
.
.
.
V=HackAction
If you are using the Scrounger ("Search again" when looting) Gene Tonic but have remapped your "R" key to something non-default, you'll need this: In section [ContainerUIActive] (about 11% of the way down the file at line 2199 for me) type "ReRollContainer" after the key of your choice. Example:
[ContainerUIActive]
.
.
.
G=ReRollContainer