Hello @cmabey,
Please follow the advice on providing a readable schematic: How to make a schematic you can post.
At the moment I have only a vague idea of what your circuit is and even less of an idea as to what the answers to your questions might be. Please post a proper schematic.
We also know nothing about the electrodes you have, please provide details.
You need to learn the difference between voltage and current, voltage is a difference measured between 2 points, it does not 'pass through' anything. Current passes through.
I think you would be better off just trying your circuit out and checking to see if you get the results you want. I consider electronics to be a great hobby for trying things and learning from what happens. As long as you use low voltages, which cannot harm you, the worst that can happen is you burn out a few inexpensive components.