Metro
 

¿Cómo se dice..?

"Ana was at the metro station this morning."

"Ana estuvo en la parada del metro esta mañana/ Estuvo Ana en la parada del metro esta mañana."

¿Los dos estan bien? ¿Estuvo o esta estaba?

Better "Ana estuvo..." (the other one may be taken as a question)

estaba/estuvo depends on your intentions. What are you trying to say? You're offering this information as, what?

To tell someone that I had seen her and spoken to her and where about she was when this happened.

Thanks

Estaba, undoubtedly, because it's contextual and not the main activity you are reporting.

You use estuvo if your goal is to inform Ana's whereabouts.

You shouldn't ask questions about imperfect and past simple without providing context and speaker's intention.