Welcome to the forum, cmills.
I'll take a stab at your questions but others will also have suggestions.
The choice of crackers and hummus as a snack is pretty expensive in terms of carb count. If you go back to Doug's book and look at suggestions for snack trays, there is a lot of variety there. In general, your carb budget should be spent on vegetables more than any other category of foods.
Xylitol is different than Splenda. Xylitol can be found at health food stores. It is technically a sugar alcohol. Sugar alcohols can be subtracted from total carbs when figuring net carbs but be careful with them. First, they metabolize before fat so they can cause
weight loss to stall. Second, they can cause "intestinal" issues that can be unpleasant.
Be careful with Splenda, too. Those cute yellow packets are 1g of carbs each because of the filler they use to make it pour the way it does. Liquid sucralose (the generic name for Splenda) has no carbs because there are no fillers needed. FTS Zero is liquid sucralose and a really great sugar substitute.
Again, welcome to the forum. I hope you like it here.