Stir the batter into the fruit, then add the nuts. Use a wooden spoon or just plunge in with your hands and reminisce about what fun it was to make mud pies when you were little. Mix it all up. You will have a mixture that is mostly fruits and nuts with just enough batter to hold it together. You can fill the pans almost to the brim because the cake will rise only slightly.
Timing is extremely variable.
Small cakes will cook quicker, larger cakes take longer. Test each cake separately, and take it out as soon as your tester comes out clean. You don't want to dry out the cake. If it starts to burn before the inside is done, cover the top with foil. You can't bake a fruitcake in a hurry.