2.5) Said open-source camera software and hardware will likely be packaged up by commercial vendors, who will happily store your data in the cloud and resell it (I mean Empower Law Enforcement) on the side. This will probably be the majority of installs.
3) Queryable in what way? If the query reveals presence/absence of a person, they already have the info they need - if it doesn't, users won't know who to pay.
4) It's easy to pretend to be a victim of crime. Stalkers can easily abuse this to find their victims. Cops are also highly-trusted by a lot of the public, and also can use this to stalk people.
5) Morally, seems bad to charge a person looking for their lost child. Less bad if it's a fixed fee, rather than deciding what to charge after hearing the request - but that goes a little against the idea of point 4 to be able to approve/deny certain requests.
6) Ubiquitous surveillance is probably still bad even when decentralized.