That's not a good idea. You don't want to connect batteries with different voltages in parallel. What happens is large currents among the batteries themselves, and some of the batteries quickly die.
When the batteries are connected in SERIES, they behave as a single battery whose voltage is the sum of their individual voltages.
When a current flows through a metal wire, the moving charges are electrons since electric current is the flow of electric charge in an electric circuit. This electric charge are therefore electrons.
