Do I use Scripts or Template? Not Sure on how templates work. Sure could use some help on this.
You can write your own script or use a template that someone else has created. Personally I would use FTP rather than TFTP but you know your own environment, so just pick what suits. And as always test your script on a lab device or one that you can get to easily to fix it
This thread has all the info
Cisco image upgrade
If it is just you using the script/template to update IOS then I would say the script might be easier. But if there is anybody else I would user a template so that there is less change of error. If you want to use templates a IOS upgrade script is a good place to start from my limited experience. Look at the templates shared on thwack and have devices ready to be broken.