Gracias Irmamar. That is good to know. Can I do the same for computadora sobremesa or ordenador sobremesa? I mean just use: sobremesa?
No, this time is the other way. You can use ordenador ó computadora and not sobremesa. Some time ago (10 years) all computers where "de sobremesa". Spanish......
Are my sentences awkward?
Not really, only two, but seems direct translations.
Mi esposo está hablando en el teléfono y él dice ¡Hola!
My husband it's at the phone and says ¡Hi!
usual: Mi marido está hablando por teléfono, te manda un saludo (he greets you, he send you a greeting)
Y mi carro es roto y en el garaje. And my car is broken and at the garage.
usual: Y mi coche está roto en el garaje.
the grandchildren are "in" the school, not "at" the school. If they were away at college, would a escuela be appropriate?
No, estarían en la guardería (Kindergarten), en el colegio (school) ó en la universidad (at the university)
If it were not, would garaje still be used and in the same manner? Garage it's usually at home, but in a broader meaning can be a repairing place (a mechanic, "un taller de reparación"): Since it's broken, can be both.
if you say "Mi coche está limpio en el garaje" it's clear it's at home.
If you say "Mi coche está roto y lo he llevado al garaje/taller" it's not at home.
saludos