Yes powdered milk has lactose. Anon91316 - where did you get the idea from that powdered milk is highly acidic? On reconstitution with water, it has a pH of typical milk - around 6.6. Its not acidic at all. Powdered milk is just milk that has 96 percent of the water removed by evaporation and the remainder is dried in a spray drier. Its nutritional composition when reconstituted with water is almost the same as regular full cream.
It's high in protein as a dry powder because the water has been removed - about 34 percent. It's not high in protein when reconstituted - about 3.5 percent.