Hi Justin,
I'd be glad to help you with your questions. If you set a script to run HOURLY, it will run on the hour (8:00PM, then 9:00PM, then 10:00PM, etc). However, the script takes a while to kick off and will not run exactly on the hour. It will probably be delayed a few minutes.
If the script is set to HOURLY and you make changes to the script while it is scheduled, make sure to save it before the script kicks off. If the script is not saved before it is supposed to run at that hour, then the changes won't take effect until the next time it's saved and ran.
Thanks,
Tyler Sidell
AdWords Scripts Team