If you create a file like this file:
/etc/init.d/.commonStuff
and put in it the commands you want to be common to all scripts: (without a '#!/usr/bin/bash' line)
# This code is meant to be included by another script.
ulimit -c unlimited
umask 027
THIS_VARIABLE="will exist once the include is completed"
export THIS_VALIABLE # And now it is exportable too
then in each script you can add these line (in a convenient place):
# Include the common settings
. /etc/init.d/.commonStuff
the leading dot is the "include some other file" indicator.
Make sure that new file is protected, (i.e. owned by root), and remove the executable flag from it to make it clear it isn't meant to be executed on its own. (Access should be no more than 644).