The quantity of batter is the easiest thing to figure out. Take one large measuring cup, fill it with a known quantity of water, and pour into the tin. Once it's full, subtract the amount of water left in the measuring cup to get the volume of liquid that fits in the tin.
Alternatively, weigh the tin, fill it with water and weigh again. Then take advantage of the fact that 1 litre of water weighs exactly 1 kg to figure out the volume of water that fits in the tin.
As for time and temperature, that comes down to the precise recipe. In general, smaller baked goods bake at slightly higher temperatures than larger, so I would start by increasing the recipe temperature by 15-20 or so degrees Celsius. As for time, I would personally just keep a close eye on the cakes and start checking for doneness (with an instant read thermometer or a cake stick) after half the time for the original recipe.