yes that guide will do it all. root, recovery, and ROM if you wish. heads up you MAY need to use deaths LGNPST method to downgrade. i had to the second time but LGMU worked the first time.
no need to buy setcpu the velcity script can be used to overclock and MUCH more (though not as many options as setcpu for OC) i find it more convenient even though i had bought setcpu i use the script. if i was you i would read through the velocity script thread as it can do ALOT for you
http://androidforums.com/velocity/287300-velocity-script.html
also anytime you are going to make a "root" related change. first MAKE A NANDROID BACKUP.