Working memory is a context that lets you navigate your surroundings and make decisions. It is memory that lets you make decisions on a small time scale. Short-term memory is encoding of information for a brief period of time without the ability to manipulate it in your mind. For example, short-term memory is what you'd use when someone tells you their phone number and you don't have a paper to jot it down. So what do you do? You can either repeat it to yourself over and over again to keep remembering it, or you can not repeat it and over time you'll forget it. Make sense? Working memory, on the other hand, would allow you to encounter something and manipulate it for a specific purpose. An example would be reading an MCAT passage. You're absorbing information, holding it in your mind for a brief period of time, and determining what to do with it.
Electrically gated channels are voltage-gated channels. I've never heard of "electrically gated channels" and a quick google search pulled up only voltage-gated channels. In my 8 years of studying and doing research in neuroscience, I've never heard anyone say "electrically gated."