these 8x 16x 18x 20x 22x thingies are the burning speed of the DVD writer. Higher speed means it can burn faster.
From this it can be concluded that the faster the speed, the stronger the diode in there. The numbers were not meant as a direct reflection of the power of the laser diodes in the DVD writers.
As for voltage, these run on red laser diodes, [highlight]so around 3v would work. (more specific is 2.7 i think)[/highlight].
Current varies with the power of the diode. 16x usually can take 300ma while a 20x/22x would go up to 400ma. (Good heatsinking required)
Lighting a match, I'm not sure about how much power is needed at least, but i think 100mw would be enough to burn a match. Maybe not very fast, but will still do it.