Should be calendar days
The no. of days should be calender days as I hear from my friends here. The AC21 provision which allows job change after 180 days of I485 filing is also calender days as I hear from my Attorney.
Regarding VSC inquiries, it is the privilege of applicant to enquire about his/her case, and I guess it should not matter how many times you enquire. The IIOs ask about our identity for the privacy of the beneficiary (you). For the privacy of the beneficiary (you), some IIOs do not disclose the status to anyone except the petitioner (Employer) or attorney.