Meaning Changes: Preterite vs. Imperfect?

Question

Are the following examples correct?

Verb focus: querer

1. I wanted ice cream. = Quería helado.
2. As I was walking, I passed by an ice cream shop. In that moment I wanted ice cream, but then I remembered my diet. = Mientras andaba, pasé por una heladería. En ese momento quise helado, pero entonces me acordé de mi dieta.

The first example should be imperfect because it's wanting in-general, but should the second be preterite because the feeling of wanting was only for a specific instant that ended immediately?

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Verb focus: tener

1. I had a dog when I was a kid. = Tenía un perro cuando era niña.
2. I had that dog for 10 years. = Tuve ese perro por 10 años.

The first example should be imperfect because it's 'had' over a vague period of time in the past, and it's in-general, but should the second be preterite because duration was stated? What if I said I only had the dog for a single instant?

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Verb focus: poder

1. He thought he couldn't come over. = Él pensaba que no podía venir.
2. He thought he couldn't come to the party. = Él pensaba que no pudo venir a la fiesta.

The first example should be imperfect because it's in-general, but should the second be preterite because it's refering to a specific instance where he thought he couldn't attend?

Answer 1

I agree with your first answer.

In the second answer, I would use imperfect in both cases. Even though "10 years" is mentioned, it has a nuance of a background in which other actions can happen.

In the third answer, I would use imperfect as well because in each case the time frame of the thought process is not really specified.