Is there a way to increase the tool face size so that the tool faces can be seen more easily on a hi res monitor (without changing the monitor resolution)?
Each of the tools has an option to set the font used in the tool output - you can change both face and font size. That is not available in PLE/PLE Plus there you can only change the face via Options>Options.
If you mean the size of the tool buttons, no this can't be changed.