1. There is no cmdlet for that if that is what you mean by 'simple' command.
You need to call the API method

2. After a Get-HardDisk you can get the sharing mode via a calculated property

@{N='HDSharingMode';E={$_.ExtensionData.Backing.Sharing}}

You can find the storage policy for harddisks with the Get-SpbmEntityConfiguration cmdlet.