Pour a cup or two of your favorite liquor or sweet dessert wine over the fruit bits, toss them, and let them sit for a few hours to absorb the liquid. This softens the fruit and creates thousands of tiny little sponges that will spread the flavor through your cake much more efficiently than mere soaking after the cake is done. A dessert wine too sweet for sophisticated palates may do just fine in a fruitcake. Most of the time I use Myers's dark rum. If you are avoiding alcohol, apple juice is a good substitute.
Walnuts are fine.
But make sure they are fresh. Walnuts turn rancid if not refrigerated. Personally I use pecans because I love them and they look pretty. Leave 'em out. I buy halves and don't chop them because I like big pieces, but it's all a matter of taste.