You use preterite to describe an action that took place and was fully done, Ex. José entro a la habitación, you can see John went into the room, he completed the action. On the other hand, imperfect tense doesn't specificate if the action was completed, Ex. José entraba a la habitación, it doesn't tell us if José fully entered the room.
Answer:
una casa veraniega is a vacation home
Vivimos en San Diego. not entirely sure if that was the correct use of the verb, but it should be :)
