no need to do a re-install

the crontabs rpm contains just a bunch of default cron files. there is no crond included so after installing crontabs you don't have a working cron installation, you just have the root crontab files

vixie-cron is the cron daemon and after installation you have crond installed

yum install crontabs vixie-cron
service crond start

and use ntsysv to start crond on boot (if it is not already set)

finally "locate" is found in the mlocate package

yum install mlocate

you could have discovered this yourself if you did a:

yum search locate