For the questions about using Splenda or any of the sugar substitutes.
The Splenda/Sugar baking mixes, both white sugar and brown sugar have instructions on the bags for substituting.
So do the Stevia/Sugar baking mixes and those with Sucralose and etc.
I have tried ALL of the baking mixes that are specified for BAKING and with excellent results.
In fact, I used even less of the mixture and substituted UNSWEETENED APPLESAUCE (purchased some very large jars) in the quick breads and muffins with strong flavors - gingerbread, pumpkin bread, carrot cake, and an APPLE CAKE! The apple cake took an additional 15 minutes of baking to get to the 210° internal temp - I am using a remote probe, inserted after the cake is fully "set" to make sure it reaches that DOND temp.
I prefer baked goods that are less sweet and even when I use regular sugars, I have been cutting down the amounts with no difference in the results except for less longevity - that is some cakes, such as yellow and white will stale faster - after 2 or 3 days but that is seldom a problem.
Cakes with chocolate or cocoa do not stale as rapidly.
I have been doing this for several years after noticing that cakes made back in the "War years" used much less sugar (which was rationed) both here and in the UK, and were perfectly fine.
What I also noticed was that in the late 1940s and throughout the 1950s, there were many cookbooks that were published with ADs by Dominos, Spreckels, American Crystal, C&H, and other SUGAR producers, that had INCREASED AMOUNTS OF SUGAR!
Merchandising of a product DROVE many of these recipes with the additional sugar and in my opinion, a lot of it is unnecessary.
