Subject/verb inversion is not required in questions, but it is the usal word order in written spanish.
Anyway in spanish subject pronouns are generally omitted so you won't notice any difference.
¿Cómo te llamas?
word order ndhus the recognition of declarative or interrogative may depend entirely on intononation
Yes there is... DL sentence is informal...
- ¿Está tu marido aquí? refers to the informal "you" ("tú");
- ¿Está su marido aquí? refers to the formal "you" ("usted").
Please notice that "su" may also refer to "she" ("ella")... context will resolve between "he"/"she" and the formal "you".