"This past week" refers to the previous 7 days (including today). Ie if today's date is September 11th, then September 4th-11th would fall within "this past week."
"This calendar week" refers to Sunday through Saturday of the current week. If today is Wednesday, then last Friday is within "this past week" but not within "this calendar week."
"This past month" does not mean all days in the prior month. At the current moment it means 31 days, but I don't know if it changes based on how many days are in the current/previous month (in February, it could mean 28 days).
I suggest you set up some dummy records in a base with date fields. Set up the filters in question, change the dates, and see what ends up getting filtered out.