It is yo trabajo because currently the verb is in infinity form but to put it in first person form you cross out the last two letters and add an o. So trabajar becomes yo trabajo.
Answer:
Cómo está? means "How are you (formal)" or "How is she/she/it?" This question is using the verb "estar."
¿Cómo es? means "What is he/she/it like?" This question is using the verb "ser."
