The infantrymen are Bashi Buzuk, first organization of local troops, not askaris. Askaris were first organized in 1888. The far right infantry is a soldier of Bande Armate, like local militia.
For the horseman I try to let you know something soon.
The soldiers depicted are not referring to 1896, in that date there was the battle of Adowa, and the dress and equipment were completely different.
Piero