Yes, "previously scheduled matter" is hyphenated when used as a compound adjective before a noun (e.g., "The previously scheduled matter was addressed during the meeting").
Pre construction - two words not hyphenated.
Yes, it should be pre-qualify.
no
Yes, "pre-school" is a hyphenated word.
No it is not, I see it both ways, pre-med or pre-medical and premed or premedical.
Yes it should be hyphenated.
It should be hyphenated. Pre-manufacture.
Pre-polishing is likely a hyphenated word.
It is not one nor two words. It is hyphenated, just as it is written in the question.
The terms pre-register and pre-registration are still used with hyphens, mainly for clarity. But most dictionaries now list the words without hyphens, as preregister and preregistration.
It depends, since some are still hyphenated, but most are not. This is one situation in which you either know or study the spelling or use a dictionary or spell check on the computer. Pre-menstrual. Preoccupied.