La entrevista salió bien, así que estoy contento.

In Spanish, salir is commonly used to talk about how an event turns out:

• La entrevista salió bien. = The interview went well / turned out well.
  You’ll also hear the same pattern with other events: El examen salió mal, La cita salió genial, etc. It’s idiomatic and very natural in Spain.

In Spain, both can be possible, but they often choose based on whether the event is seen as finished in a completed time frame.

• Salió bien (pretérito) often sounds like a completed, closed event: the interview is over.
• Ha salido bien (pretérito perfecto) is also common in Spain when the speaker feels it’s connected to the present (e.g., “today/this morning/just now”), even if the interview is finished.
  Both can be correct; salió bien is perfectly normal here.

Así que means so / therefore / as a result and introduces a consequence.

• La entrevista salió bien, así que estoy contento. = The interview went well, so I’m happy.
  Entonces can also mean “so/then,” but it’s often more conversational and can also mean “then” in a time-sequence sense. Así que is very clear cause → result.

It’s very common (and usually recommended) to use a comma when así que connects two independent clauses:

• La entrevista salió bien, así que estoy contento.
  In informal writing you might see it without the comma, but the comma helps readability.

Spanish typically uses estar for emotional states as current feelings:

• Estoy contento = I’m happy (right now / about this situation).
  Soy contento is not the normal way to say “I’m a happy person” in Spain. For a general personality trait, Spanish would usually use something like Soy una persona alegre or Soy muy optimista, etc.

Contento/contenta agrees with the speaker (or the person being described):

• Male speaker: estoy contento
• Female speaker: estoy contenta
  Plural: estamos contentos/contentas (or mixed group usually contentos).

Both work, but they have slightly different feel:

• contento = pleased, happy, satisfied (very common for good news or a good result)
• feliz = happy (often stronger, more “joyful”)
  So this sentence sounds very natural with contento because it’s a satisfaction with how it went.

Yes—Spanish normally omits subject pronouns because the verb ending already shows the person:

• …así que estoy contento. (most natural)
  You’d add yo for emphasis or contrast: …así que yo estoy contento, pero ella no.

Spanish usually uses the definite article more than English when referring to a specific known thing:

• La entrevista salió bien = The interview went well (the one we’re talking about).
  You might omit it in headlines or very telegraphic style, but in normal speech/writing la is expected.

Yes, and it’s very common:

• La entrevista salió bien, así que me alegro. = The interview went well, so I’m glad.
  Me alegro focuses on “I’m glad” (reaction), while estoy contento states the emotional state.

With verbs like salir, ir, estar, hacer, etc., bien/mal usually comes after the verb:

• Salió bien. / Fue mal. / Está bien. / Lo hice bien.
  You can sometimes move adverbs for emphasis, but the neutral, most common position is after the verb.