post configuration of InstaDMG created images – best practice

We've had a lot of discussion about instauser, ARD kickstarting, eliminating the install video, eliminating the registration screens, enabling the root account, even directory binding on this forum. I've seen a few comments about using StartupItems and others about launch agents to accomplish these goals. Can we start some discussion about best practice, standardizing methods, etc? For example, I have a shell script I use to kickstart ARD. I want to implement it for running the first time a newly imaged machine boots. My questions about this would be... 1. StartupItem vs. launch agent? I think the answer is obvious. StartupItems are almost deprecated, so launch agent it is. Even if I'm making 10.4 images, it seems short sighted to spend time on a StartupItem. 2. What is the best method for creating the launch agent plist file - manually, Lingon, something else? What are people using to do this? 3. If most of these tasks are to be accomplished via shell script, what location is best for storing the scripts? /Library/Scripts/ ? Someplace else like /etc or /var? Hopefully these queries will spark some debate. Let's define these things, no?