The ampere (A)is an SI base unit and is defined as:

"The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 × 10-7 newton per metre of length."

The volt (V) is an SI derived unit and is defined as:

the SI unit of electric potential. Separating electric charges creates potential energy, which can be measured in energy units such as joules. Electric potential is defined as the amount of potential energy present per unit of charge. Electric potential is measured in volts, with one volt representing a potential of one joule per coulomb of charge. The name of the unit honors the Italian scientist Count Alessandro Volta (1745-1827), the inventor of the first battery.

See: http://www.unc.edu/~rowlett/units/

for further info on units

High currents do not necessarily mean high speeds of the charges themselves. In typical wiring the average "drift rate" of charge for DC is less than one inch per second.

Where did you get the inch per second figure from? I understand and prefer to know these things in SI units. I loathe converting FFU (Fred Flintstone Units) to SI as their is a high probabilty the FFU is wrong to begin with. There is a tendancy when converting SI to FFU to round the result to give the impression of neat numbers in FFU. Thus, when attempting to return to SI, the numbers are not the original.

Electric current is indirectly a measure of the number of electrons passing a given reference point in a unit time of one second. Since the ampere is also equal to (but not defined as) one coulomb of charge moving per second, and there is a fixed number of electrons per coulomb (approximately 6.241 506 x 10^18), one can see that current is the amount of electrons moving and not the speed at which they move (speed being in units of metres per second).

The actual electron speed varies with the medium it is moving through and I believe it is equal to the speed of light when in space (299 792 458 m/s exactly).

coulomb (C)

the SI unit of electric charge. One coulomb is the amount of charge accumulated in one second by a current of one ampere. Electricity is actually a flow of particles called electrons, and one coulomb represents the charge on approximately 6.241 506 x 10^18 electrons. The coulomb is named for a French physicist, Charles-Augustin de Coulomb (1736-1806), who was the first to measure accurately the forces exerted between electric charges.