change the default access right for nouser folders and files in Red Hat Enterprise Linux

Issue

We found there is folders and files in system which is by default without owner or writable to anyone.
We’d like to know why the below folders or files are set with such access rights by default?
Is it safe for we restrict the access to those file to harden the system? If can not, any reason can be explained?

World writable folders: 
#find / -perm -0002 -type d -print
/var/log/dumps, /dev/shm

World writable files: 
#find / -perm -0002 -type f -print
/selinux/member
/selinux/user
/selinux/relabel
/selinux/create
/selinux/access
/selinux/context

Files with no user or group:   
#sudo find / -nouser -o -nogroup -print

/usr/bin/ssh-agent
/usr/sbin/postdrop
/usr/sbin/postqueue
/usr/libexec/utempter
/var/lock
/var/spool/postfix/public
/var/spool/postfix/maildrop
/var/spool/postfix/maildrop/25C1E13403A
/var/cache/man/X11R6
/var/cache/man/X11R6/cat7
/var/cache/man/X11R6/cat9
/var/cache/man/X11R6/catn
/var/cache/man/X11R6/cat4
/var/cache/man/X11R6/cat8
/var/cache/man/X11R6/cat5
/var/cache/man/X11R6/cat6
/var/cache/man/X11R6/cat2
/var/cache/man/X11R6/cat3
/var/cache/man/X11R6/cat1
/var/cache/man/cat7
/var/cache/man/cat9
/var/cache/man/catn
/var/cache/man/cat4
/var/cache/man/cat8
/var/cache/man/cat5
/var/cache/man/cat6
/var/cache/man/local
/var/cache/man/local/cat7
/var/cache/man/local/cat9
/var/cache/man/local/catn
/var/cache/man/local/cat4
/var/cache/man/local/cat8
/var/cache/man/local/cat5
/var/cache/man/local/cat6
/var/cache/man/local/cat2
/var/cache/man/local/cat3
/var/cache/man/local/cat1
/var/cache/man/cat2
/var/cache/man/cat3
/var/cache/man/cat1
/var/cache/cups
/var/cache/cups/job.cache
/var/cache/cups/rss