There is a common metaphor where electricity is compared to water in a pipe. Ampere's/Amperage/Amps/Current are likened to the flowrate of water
and
Voltage/Volts/Potential/Potential-Difference are likened to the pressure at which the water is delivered
This page does it better than I can -
Water circuit analogy to electric circuit
imho this metaphor fails when you have an open circuit (the water/electrons dont just fall out the end) or a short circuit (the water/electrons dont just happily run in a circle - the source supplies all the current it can and heats up the wire/connections/batteries until something fails or the source (battery) runs out of current.
To answer your questions:
Lightbulb - house wiring (AC) is not like a battery - the electrician terms are "hot" and "neutral". the hot comes from the pole outside the house, and the neutral is normally grounded - the hot and neutral normally have 120v (rms- its a sine wave...) between them.
You as a person are normally grounded becuase your feet touch the earth - you are normally at 'whatever voltage' the neutral is.
So in the light socket, you have the ring (threaded area) and the tip. normally the tip is wired to hot (its the smallest contact area) and the ring is wired to neutral - so when screwing the bulb in, you *might* touch the ring (which is at the same voltage as you) but you'll never touch the tip (which is 120v different than you)
You'll find the same thing in a car's cigarette lighter plug - the outside of the female end if negative (ground- same voltage as the car chassis ) and the center pin is +12v.
If the socket is wired backward, then the ring will be at 120v and you would get shocked if you touched it.
AC is funny becuase instead of the electrons flowing just one direction, they go from "full speed one way" to "full speed backwards". We did this becuase it is easier to generate and move electricity long distances using AC instead of DC (less loss, simple generating machine...)
The net effect is the same - a Battery (DC) makes voltage, which applied across a resistance/load consumes current (Amperes) and does work (makes light/spins the motor). AC, when applied across a resistance, consumes current and does work.
I like AC becuase you can make unidirectional devices (diodes, AC electric motors) that take advantage of the AC's changing nature and use this to do things that you can't do with DC (example: if you put wrap 2 lengths of wire around a metal bar, you can make a transformer, which easily changes AC voltage up or down with little loss - there are at least 5 of these between your house and the nearest power plant.
if you put DC into a transformer, you'd just make a weak electromagnet.
I'm horrible at explaining these things. Maybe someone else has a better post by now...
-John