1.what is rc_status

The commands from rc.status are actually SuSe specific I think. AFAICT they handle two things: output to the user and the final return status of the script. rc_status checks if the previous command (i.e. the start/restart/stop of a service)executed successfully and sets the "status value"

You can conceivably write your shell script without them, but I assume they help making sure that your script conforms to LSB requirements and blends in well with other system scripts. I bet most of this is actually documented in the 

2.what is checkproc

NAME

SYNOPSIS

checkproc [-v] [-k] [-n] name_of_kernel_thread

pidofproc [-k] basename_of_executable

REQUIRED

/full/path/to/executable or name_of_kernel_thread

Specifies the executable which processes should be found, or alternatively, if the option Or alternated, if option -n is used, the name of the kernel thread. This argument is always required.

EXAMPLE

checkproc /usr/sbin/sendmail

returns all pids of running sendmail processes.

checkproc -p /var/myrun/lpd.pid /usr/sbin/lpd

returns the command line or the basename of the process pid found in /var/run/lpd.pid.

EXIT CODES

0

Program is running

1

No process but pid file found

3

No process and no pid file found

101

Wrong syntax on command line

102

Other errors

If the option -k is used checkproc uses exit codes like (8) or (8) do:

0

Program is running

1

Generic or unspecified error

2

Invalid or excess argument(s)

4

Insufficient privilege(s)

5

Program is not installed

7

Program is not running

in some cases a message is send to standard error or, if no standard error available, (8) is used.