I am looking for information on students at military schools and academies (pre-1918)

The record group “Militärerziehungs- und Bildungsanstalten” may contain less information for biographical research than one would expect. The archives of the “Theresianische Militärakademie”, for example, were badly damaged by fire in 1920.

Classification lists, where preserved, are the most important source for a student’s trajectory. Logically, you first need to identify the school/academy which the person (presumably) attended.

There are useful lists of students at the “Theresianische Militärakademie” with short biographies:

Svoboda, Die Theresianische Militärakademie und ihre Zöglinge 1894-1897 (Volume 1, Volume 2, Volume 3).

Lists of students at the “Technische Militärakademie” are provided by:

Gatti, Geschichte der k. und k. Technischen Militär-Akademie. 1. Theil, Geschichte der k.k. Ingenieur- und k.k. Genie-Akademie: 1717-1869.

Gatti, Geschichte der k. und k. Technischen Militär-Akademie. 2. Theil, Geschichte des k.k. Bombardier-Corps, der k.k. Artillerie-Hauptschule und der k.k. Artillerie-Akademie : 1786-1869.