(10) FALSE
As we learned in the context of Gauss' law, any excess ELECTROSTATIC charge on a conductor must reside on its surface. Once we are dealing with a situation of moving charges (non-zero currents), then our previous argument no longer applies, and excess charge can be found throughout the volume of a conductor.

(11 & 12) TRUE, FALSE
Positive charge moving up and negative charge moving down BOTH make the same-sign contribution to i = dq/dt.

(13 & 14) Both FALSE
An ionized gas or the electrolyte in a battery can have currents of positive or negative ions of various types. In contrast, the only way in which a conducting wire can carry an electric current is for electrons to move along it. When positive ions reach the top plate in the ionized gas scenario, they neutralize by acquiring electrons from the plate. The electrons which move along the wire to replace the neutralizing electrons are essentially the continuation of the current carried by the positive ions.