Thanks for the great questions! In general, the “Runbook Only” layout is just a cosmetic difference, minimizing the deployment-based options, as opposed to any functional changes.
Is it possible to have “Runbook Only Project” and still include “Script Modules”? (For use in the Runbooks.)
Certainly is, yes, you can include script modules on the Process page of your Runbook as normal (this is only shown if you have script modules configured already).
Is it possible to change the Lifecycle of a “Runbook Only Project”?
By default, Runbooks can run against any available environment - this can be changed from the Settings page on your Runbook to specify certain environments, or to use the lifecycle associated with the Project (if one is configured in the deployment process)
I hope this helps, and please let me know if you have any further questions!