Here are the answers with explanations:
Where have you been?
Explanation: The present perfect tense (have/has + past participle) is used to ask about someone's whereabouts over a period of time.
Chris hasn't made any plans for his birthday yet.
Explanation: "Yet" indicates that something hasn't happened up to the present time, so present perfect (has/have + past participle) is appropriate.
Sally lived in London when she was young, but she has lived in Paris since she was sixteen.
Explanation: The first part refers to a completed action in the past (lived), so we use the past simple. The second part uses "since" to indicate a duration from a past time to the present, so present perfect (has/have + past participle) is used.
Have you ever tried Japanese food?
Explanation: "Ever" is used with present perfect to ask about experiences in someone's life.
I usually meet Adam every day, but I haven't seen him since last week. We spoke for five minutes on the phone yesterday, though.
Explanation: "Since last week" indicates a period from last week to now, so the present perfect is used (haven't seen). "Yesterday" indicates a specific time in the past, so past simple is appropriate (spoke).