Can trusted emergency contact on premium account view all vaults and add items? Or do I need to set up an organization? Will this level of participation allow my husband and I to share one account and all passwords?
There are two possible configurations for emergency access: View (emergency contact can view all vault items in read-only mode) or Take-Over (emergency contact sets a new Master Password, which automatically replaces the existing Master Password disables 2FA; the emergency contact now becomes the new owner of the vault and has both read and write permissions — exactly as they do on their own vault). I don’t think either of these options will be suitable for your use-case.
The Terms of Service do not permit a single account to be used by more than one person, but I am aware that there are Bitwarden users who do this, anyway.
The option that is best suited for you is indeed to set up an Organization, and then place all of your shared passwords in a “Collection”.