Looks like you already have it sorted out, but here's some more:
Some super easy subs for dairy: Earth Balance spread or buttery sticks (but remember they're salted, so don't add any more salt to your final dessert), even Crisco. The fatty top of coconut milk whips into a beautiful whipped cream that tastes and feels like the original (aka not coconutty) and there's a coconut oil Cool Whip alternative called CocoWhip that's better than Cool Whip that you can get at WF. Full fat coconut milk can be used as sub when making stuff like caramel where you'd use heavy cream. Be aware with chocolate - milk chocolate always has dairy (unless you get vegan milk chocolate), semisweet and dark are safer, but check the bag. They HAVE TO list dairy since it's an allergen. HEB even has evaporated soy milk and sweetened condensed soy milk, which won't make a difference in flavor in your recipe unless your recipe is straight up sweetened condensed milk in a bowl.
Look up vegan stuff - Isa Chandra Moskowitz and Minimalist Baker have good dessert recipes that are easy and take the brain work out of having to figure out what to sub. I'm vegan and sub in Earth Balance, homemade butter, coconut milk, soy milk, and sweetened condensed soy milk all the time and everything always turns out (but I also have a keen eye for filtering out bad recipes in the first place).
For ice cream, Ben and Jerry's has almond milk based ice cream and there are other brands like So Delicious and Coconut Bliss that use coconut (again, it does't taste like coconut, coconut is actually a super mild flavor), and Arctic Zero which isn't dairy free, but is lactose free AND super low in calories if they/you are health conscious.
As a person with dietary restrictions, thank you for taking the time to ask people about this and accommodate your guest!
