Present perfect simple or continuous?

The simple form: what is done

• results and numbers: I've visited six cities. I've lost my umbrella three times.
• finished actions, often with already, just, yet, ever, never: Has the mail come yet? (American English often uses the past simple here too: Did the mail come yet?)
• state verbs, which are not usually continuous: know, own, believe, like, want, need, understand, belong, be: I've always liked jazz.

The continuous form: what you have been doing

• an activity up to now, often with how long, for, since, all day: It's been raining since Tuesday.
• a repeated activity up to now: We've been getting up at five every morning.
• a recent activity with signs you can see: You look tired. Have you been working late?
• an activity that may not be finished: I've been reading your book (I'm in the middle of it). I've read your book (I finished it).

Both forms are fine

With live, work, study, teach + for or since, both are correct; the continuous sounds more temporary: My parents have lived / have been living in Texas for twenty years.

One verb, two meanings

Some verbs are state verbs in one meaning and action verbs in another: I've had my bike since college (= owned). Lately, I've been having problems with the brakes (= experiencing). · I've always thought he was right (= believed). I've been thinking about you (= had you in my mind).

How many…? How much…? → the simple form. How long…? + an activity → usually the continuous: How long have you been waiting?