回复：Question to an on-site interview

For the experienced candidate, the interview process should be a chance for you to ask the questions you have about tthe employer.
Yes, you can ask questions about why they open this position now durinig the interview.
Usually the salary will not be mentioned duing the first interview, or even not in the second interview.
It will be discussed until the last stage when the candidate passed all the previous interview and was not turned down due to the unproper answer about the salary (ask too high).
The goldern rule is: whoever mensioned the salary the first time, who is the looser (inicluding candidate and the emplyer).