a) Mrs. Wiggins didn't specify in the original recipe if she toasted the nuts for the cake. I really love the flavor of toasted nuts, and recommend that you toast them if time allows. Place on a sheet pan in a single layer and toast in a 350°F oven for 6-8 minutes, then cool completely before adding to the cake.
b) The original recipe calls for chopped bananas. Roughly mashed bananas will also work in this cake.
c) If needed, add heavy cream, half & half or whole milk 1 Tbsp at a time to thin the frosting to spreading consistency.