Do Jews smoke (genuine question - I have no idea if there is a religious proscription against smoking)? How do they light up on the Sabbath?
Not on the Sabbath.
Do they sit in the dark after sunset? Do they light candles - if so, how?
The Jewish Sabbath runs from sunset to sunset -- they light candles just before the sun sets. By the time it gets dark enough to need them again, the Sabbath will be over. If for some reason the candles go out,... yes, they sit in the dark.
Do they watch television? Listen to the radio? Surf the internet?
Sometimes, sometimes, and no. If the "fire" has already been started, you can leave it going -- so if the TV is already on at sunset, you can leave it. (In fact, I believe that you're not allowed to turn it off, for the same reason you can't turn it on.) But you're also not allowed to change channels, so you better REALLY like the Shopping Network, 'cause it's going to be on all night and all day.
If so, how are these sparks different?
No one's "making" them. Similarly, riding in the elevator is okay as long as you don't need to press any buttons or throw any switches. Similarly, there are stoves with "Sabbath modes" that you can turn on and leave running all night and day (essentially, by disabling the safety interlock that would normally turn the stove off after it's been running for X hours).
The "Sabbath" elevator is all right because it runs all by itself, up and down, opening and closing the doors at each floor, so you don't do anything to it (like push a button).