When can you NOT replace milk with almond milk?
In baking, you can almost always replace cow's milk with a non-dairy product.  It's usually a matter of taste.  In stove-top cooking, you may have to experiment more, especially if making creamy sauces.  In that case, thicker, non-dairy milks should be tried.  Here, again taste will probably be important, but it is probably important to pay attention to viscosity as well.  Even foods based on dairy, like yogurt and ice cream, can be made with substitutes.  Consider that many non-dairy milks are sweetened, so you will want to factor that in as well.
If you are avoiding dairy, you can always find a work-around.  In some cases it will not be noticed, in others, the result might be a little different, but that doesn't mean it can't be delicious.
Having said this, scrambled eggs can easily be made with no addition of dairy, and most pizza doughs that I am familiar with do not use dairy either.  So, those preparations are easy enough to deal with in this regard.