Yes, an agent is just a way to say, actor, or person participating in the system.
Everything on expanse cost expanse for computational power,storing data for instance like a users credentials will be stored in the blockchain.
The expanse dao is mostly to control the 10m exp reserve, however we plan to release tools where users can couple the native borderless services with their own means of rule. Means of rule like, some people might like democracy, others oligarchy others their own flavor or mixture. Borderless aims to be the platform where people will have the right to choose.