For the first question, you're dealing with two different pedagogical generations of understanding acid solutions in water. A long time ago, when I was taking general chemistry, dirt was old, and dinosaurs were just being invented, acidity was expressed in terms of [H+
] in water. Shortly thereafter, with the argument that free protons couldn't possibly exist in water, acidity began to be expressed as [H3
], drived from the formalistic reaction
In simplistic terms, "hydrogen ions" and "hydronium ions" in a water solution are the same thing; your reactions are probably sufficient.
For the second question, start with the first part - what did you observe when you added the two powders together?