Hello iBrummie,
Regarding the Accounts and their sites, you can always use accounts and sub-accounts. To achieve this you should create the main Account in CRM and afterwards you can create the sites using the account entity as well and afterwards linking them with the
main account using the "Parent Account" lookup field.
About the ownership, CRM's security model works essentially with:
- Business Units
- Teams
- Users
- Security Roles
This depends entirely on the way your company works but what I would do (assuming that the accounts information is shareable in your company) is to make the sales accounts the owners of the records and provide read/write access at a business unit level to
the office managers.
Here is some more info on the matter:
Security concepts for Microsoft Dynamics CRM
How role-based security can be used to control access to entities in Microsoft Dynamics CRM
Please mark as answer if I managed to help you.
Regards,
Pedro