Internal Email Notifications

I'm looking to have the email notification system adapted so that:

• The main thing we're looking for is having friend notifications appear in the internal email system on the Dolphin install

In addition, we'd like:

• if a member has email notifications turned OFF, they receive the notifications in their Dophin internal email acct only.
• if a member has email notifications turned ON, they receive the notifications in their Dolphin internal email acct as well as their external email
• a selector for the member to choose to receive or not receive notifications in external email and in internal email separately ( so it would appear as: do you want to receive email notifications in your mailbox here on the site? ____yes _____no / do you want to receive email notifications at your email address that you registered with? ____yes____no
• ideally, I'd also like to limit the number of email notifications, for example one notification for any one subscription or other notification until they log in next. So that if there are 20 updates to a group in an hour they do NOT get 20 email notifications.