Can homeowners attend the meetings where we discuss management proposals?

Depends on your state and your documents. Many state acts require open Board meetings with limited executive session exceptions, and contract negotiations are sometimes an allowed exception and sometimes not.

Practically, most Boards evaluate proposals in executive session where permitted and take the vote in open session, which keeps the deliberation candid while keeping the decision on the record.

Check your act and your bylaws before assuming either. Getting this wrong is a procedural challenge waiting to happen.