1)
Have you arrived already? Correct
Yes, I have already arrived. Correct
No, I have not already arrived.-No I haven't arrived yet
2)
John, where are you?
I am already there. Correct
Present perfect with already, yet, just
Already usually comes before the main verb
Just comes before the main verb
Yet comes at the end of the sentence in questions and negatives....
eg: a) Have you done your homework yet?
b) Yes, I've just done it or No, I haven't done it yet.