When it comes to substitutions, I wish I could answer each and every one of your questions. Unfortunately, I can't. You see, I don't have a crystal ball with the answers; they're not in my head, they're in my hands, but I'll get to that later.
For me, baking involves the use of techniques and ingredients that come together in a magical way –each recipe is unique. Like my hero Virginia Satir, I believe in “leading the change process a half a step behind,” which has meant learning to use my senses and see what is called for in each recipe. In some ways, my recipes develop themselves as I test them. I let things happen and unexpected outcomes can be my friend during this process.
This observational experience in which I arrive at answers by using my senses –of sight, touch, smell and taste (sometimes sound too) is an organic process. I test and test my recipes until I arrive at something that appeals to me. After that, I give samples to my family. If they approve, I test the recipe without changing it, a few more times just to make sure I have something that is reproducible.
If you are looking for a substitute, I encourage you to validate these findings for yourself through trial and error. Feel free to experiment with the ingredients in my recipes and customize them to your needs, whatever those may be.
If you like to customize recipes to your individual preferences in terms of taste and nutrition, by all means, go wild and experiment! Just make sure to stop back by and leave a comment on your alchemical experience –and let us know your results.
So here's my answer to your substitution questions. I don't have a magic wand that I can wave to come up with the answers. But that doesn't mean you can't find them –just get out that bowl and spoon and start stirring!