Bachmann part Number BAC42240
What's the voltage and current rating per bulb?
How should the be wired?
I am not sure of the exact answer but it looks like no one else is either. Voltage rating is most likely 12 to 16 volts. Current rating could be as low as 65 mA but more likely around 100mA. They should be wired in parallel across the ac output of a power pack or a wall wart transformer (ac or dc - doesn't matter which.) At 16 volts, the life is probably around 200 to 500 hours. The corresponding life at 12 volts would be 8000 to 20,000 hours but the lights would not be quite as bright.
For lighting buildings, I like to use miniature Christmas tree lights. The bulbs that come 50 or 100 or 200 in a string are rated 2.5 volts, 65mA. I like to put 5 or 6 of them in series in a "mini string" and connect the mini strings in parallel across a 12 volt supply. With small houses, I usually use two bulbs so one mini string will serve 3 small houses. For larger buildings, I usually put in more bulbs for even lighting, often a whole mini string.
I do not recommend using a 50 bulb string to light a whole town at once. That would put 120 volts under your train table and that is just too risky. Better to break it up into 12 volt mini strings and run them on a safe voltage.
With so many people converting to LED Christmas lights, strings of the mini lights are available for the asking.
Jim
Jim