Hi Deb!

I'll try to answer at least a couple of your questions. The questions on the specifics of insulin are a bit beyond me, but you can try checking Dr. Bernstein's website to see if there are any updates to help you there or you can send them a question directly. The website is www.diabetes-normalsugars.com
The Splenda in the box and packets does have a filler like the other sweeteners in packets, so you would have to count the carbs in it if you do decide to use it. The granular Splenda in the box has 24 grams of carb per cup and the packets are usually counted as 1 gram of carb each. Otherwise, you can use the tablets like Dr. Bernstein suggests. There is a push to get liquid Splenda (which has no carbs) available to the general public, but it may be a while before it happens. Liquid Sweet-N-Low might be another option.
I believe that Dr. Bernstein recommends that type 1's not snack because of the additional insulin requirements that it would present.