I think the risk of these things happening is relatively low.
Taking antacids for a longer period of time can have horrible effects on your stomach acid and digestion :/. It can permanently lower your stomach acid, hence you won't be able to break down and absorb nutrients from foods. Been there and it is a difficult task restoring your stomach acid.
You can drink a teaspoon of baking soda in water to help heartburn. It works quickly and is not as aggressive on your stomach acid.
I don't have acid reflux this time around but what I keep reading on Paleo forums is that many moms are able to keep it away by strictly avoiding Gluten. This shouldn't be hard as you can find any product Gluten Free. Cookies, bread, noodles etc. (the bread tastes better toasted!)
When I had a stomach infection last year from antibiotics (side effect) I even had to eat lower in carbs, specifically avoid starches for a while. I also ate lots of Gelatin (bone broth, home made jello sweetened with honey or stevia) to coat the irritated stomach lining.
Here is some general advice for reflux that seems to help many:
-No grains, especially gluten. However, later in pregnancy I would try some sprouted bread or sour dough bread (available at whole foods)
-Low carb in the morning, higher in fat (good fats that do not -cause heartburn - butter, coconut, olive oil, palm oil). Save your carbs for the evening.
-Try eliminating foods high in FODMAPS.
-Steaming and boiling are better than frying and baking.
-Bone broth in the morning among other foods.
And if your digestion isn't doing perfect consider adding digestive enzymes and probiotics to help your nutrient absorption. Restoring stomach acid with supplements I imagine to be difficult in pregnancy.