'have you been staying' vs 'will stay'

[Attila]

Hi All,

If somebody ask me 'How long have you been staying here?'
then he wants to know the numbers of the days between my arrival and today.

the answer could be on that question: for seven days or since one week

If somebody ask me 'How long will you stay here?'
then he wants to know the numbers of the days between today and my departure.

the answer could be on that question: for two days or till the day after tomorrow

Is the above correct? If not please correct me.

[Torsten]