I published a video that provides an overview for reviving/resetting dead AI in loaded/unloaded streaming level environment as well as handling those same events when the streaming level is always loaded. Note that there is no additional logic required for the first part of the video: loading/unloading streaming level, other than the load/unload logic.
In regards to the AI variables that are to be saved, that is mostly user specific, so I cannot provide a general checklist that will cover every project. The primary variables to take note of are: Health, Current State, and Target Actor (If you plan on having Initial State set to Pursuit upon loading). The AI’s current location might also be beneficial.
I hope this helps.