Why are you not reading the CA-7 manuals for your questions? If your site is licensed for CA-7, you have access to the manuals.
I'll give you the first one. The rest of your questions, you need to start reading to learn the answers yourself.
From the CA-7 Database Maintenance Guide
manual, Date and Time Scheduling, on page 43 of the version 11 manual:
Base calendars define available processing days for the installation. Any
number of base calendars can be defined. However, it may be possible to
satisfy installation requirements with only one or two calendars.
Each calendar defines a single year with a starting and year-ending boundary
that can be crossed only in the first or twelfth month. A given calendar can
represent schedule months in either standard or user-defined format (for
example, accounting, fiscal, and so forth).
Base calendars can be generated through either batch or online facilities. To
use the online facility (DB.2.8), a Unicenter CA-7 calendar PDS must be
allocated and identified to Unicenter CA-7. For information about enabling
online calendar maintenance, see the Systems Programmer Guide. Processing
of base calendars for resolution of schedules is the same regardless of whether
they were generated using the batch or online facilities.
Calendars can be generated through the Unicenter CA-7 CALENDAR macro.
Macro keywords are used for calendar definition and the macro is assembled
and link edited using standard procedures. Base calendars are link edited to the
Unicenter CA-7 LOADLIB or a specified calendar library, and are stored in the
form of bit masks that represent available and unavailable processing days for
Timing for generation of base calendars is flexible. The only requirement is that
a particular calendar exist before resolution of work schedules related to the
calendar is attempted. Base calendars must be regenerated whenever available
processing days change and before the beginning of each year. Generally, next
year's base calendars should be generated by July 1 of the current year. New
base calendars can be generated at any time without impacting current
processing schedules. Schedule resolution, described later, is used to change
the processing schedules, for jobs or networks, with a new year or changed
PRINT Command: Use the PRINT command to produce a month-by-month
listing of indicated base calendars. PRINT produces output that reflects the
beginning and ending days of each month, holidays, or any other
nonprocessing days that were defined when the calendar was produced. The
PRINT command is described in the Commands Guide.