Hello!

As for the cruise, it's absolutely critical you call ahead and talk directly
with someone who can supervise your meal preparation in the kitchen. Many
operations that feed people on the scale of a cruise ship are actually very
good at handling allergies--but you *have* to talk with them first. Also, be
specific, and be very clear in communicating your needs. Calling ahead also
allows you to keep from feeling left out of the fun on your cruise--it
really is OK to say, "What can we do about dessert for me?" so that you're
not looking at the same tired option every meal while your tablemates order
elaborate concoctions with exotic names!
 For your other questions ... many of the milk substitutes I use personally
contain soy, and so wouldn't work for you. But, some surprising options
exist. For example, for cold things (like buttering bagels), ripe avocado,
with a little salt and pepper if you like, makes a wonderful substitute for
butter or cream cheese! I also like olive oil, usually with a bit of garlic
and whatever herbs strike my fancy in it, on good bread.

I'm fond of Italian salad dressing on a baked potato, because it adds the
fat and flavor I want without any dairy. I started that because most
restaurants are able to come up with it even on short notice. Just make sure
to check the ingredients first, as some Italian dressings contain cheese.

For the tacos, I'd go for avocado again, this time in slices.

One thing I've discovered is that most fake cheeses aren't very good, to my
taste. I'd rather find something else with a good flavor to use instead. To
replace cheese, think "fat" and "flavor" together ... it's healthier to
avoid the fat, but remember it was there in the cheese in the first
place--alternatives that omit it usually aren't as satisfying.

I hope this helps!

Weavre Cooper