couple newbie questions...

The smoke ring is a bit of a misnomer. As I understand it it's more of a chemical reaction that comes from nitric acid buildup in the outer layers of the meat formed when nitrogen dioxide from the wood smoke mixes with water in the meat. So, unless you have some wood chunks I doubt you will have much of a smoke ring in an electric smoker. Possibly, some from grease drippings.

As for your second question I can't answer that one.

You can get a so called "smoke ring" in an oven.

If you want to impress your friends, provided they understand the status of a smoke ring and you are not proud, then you can rub tender quick on a brisket and let is sit for 10 to 15 minutes then rinse it well. It will have a bit of a gray color raw but will be fine when cooked and the tender quick will not affect the taste so season it as usual. I have done this with brisket as an experiment I learned here and it worked fine but I have not tried it on other meats. I know this is not what you are looking for but if you feel you just got to have the ring this will work, personally I don't care if I have one or not just good smoked meat. I am sure you know if you want the smoky taste you will have to use some form of smoking wood in the electric smoker, be it chips or chunks.
Dave