Family Sharing and iTunes Purchases with different AppleIDs

There is no point using family sharing if you are all going to use the same ID for iTunes, however I suggest you don't share an ID for iTunes and use family sharing instead.

Firstly, you'll need to add a card to it before you can use it for a family sharing set up. If you do use it for family sharing, you will need to add the ID as a user that did buy all the content before you can share the content that belongs to it.

Once you set up family sharing you will be given the option of inviting others to the family set up.

That's what I'do tend to do if I understand you proper.

If you are saying you have ID 1 under which you bought all your music and apps and ID 2 which you now use for contacts, calendars etc, then I'd use ID1 and move all my contacts etc across to ID 1 and only use that DRM now on.

If you are also saying ID 1 is a me address, it doesn't matter, its also an iCloud address too (but an iCloud address isn't necessarily also a me address if you get what I mean)

Once you use ID 1 for a family share you can invite the rest of the family using their own individual ID's and share your purchased content with them.

What makes you think using a gmail account as your primary ID has any less features than using an iCloud address.

If your photos are in photos on your Mac you should be able to move them from the iCloud Photo Library for one ID to the library of another.

Moving your iCloud data from one Apple ID to another is achieved more easily on a computer than it is on an iOS device, indeed certain aspects of the move can only be done on a computer. However, whichever device you choose to move your data on, you should do so by turning individual iCloud services off one at a time and not sign out of the account until all services have been turned off and dealt with. (Settings > iCloud on a mobile device and system preferences > iCloud on a Mac)

If you have purchased extra space for iCloud under your previous Apple ID, this won’t be transferred when you change the Apple ID you use and you will need to re-purchase the required space under the new Apple ID.

iCloud Drive. Save data from your iCloud Drive to a computer before turning off this service. You can use the Finder on a Mac or through iCloud.com if you use a PC. Simply move the data to your new Apple ID once it is set up.

Photos. Make sure you download and keep originals when prompted when you turn iCloud photo library off, you want the photos to remain on your device and merge with your new library when you set up your new Apple ID.

If you use photo stream be aware that there may be more photos on your device than there are in the cloud, photo stream in the cloud only keeps up to 1,000 photos for 30 days, if you have older photos or more than 1,000 on your device you may want to copy them to a computer before turning photo stream off.

If you have created any shared albums you will need to create them again once you have set up your new ID, any photos that anyone else as added to your shared albums should be imported to your camera roll/library before you turn off shared albums.

Mail. Once you change your Apple ID, you will have a new iCloud email address. So that you don’t miss any mail which is sent to your old address, you can arrange to have it forwarded to your new address (or any other address), you can set this up at iCloud.com > mail > preferences > general.

Contacts. You will be given the opportunity to save contacts to your device when you disable this service, merge them when prompted when you re-enable the service after signing into your new Apple ID.

Calendars. You will be given the opportunity to save calendars to your device when you disable this service, merge them when prompted when you re-enable the service after signing into your new Apple ID.

Reminders. You will be given the opportunity to save reminders to your device when you disable this service, merge them when prompted when you re-enable the service after signing into your new Apple ID.

Safari. You will be given the opportunity to save Safari Data to your device when you disable this service, merge them when prompted when you re-enable the service after signing into your new Apple ID.

Notes. You cannot save notes easily. On a Mac you can drag them into a different account and then drag them back once you have set up your new ID, but on an iOS device you will essentially need to copy and paste them into new notes when you have set up the new Apple ID, but you will need to share them before you turn of notes for the old Apple ID, either by messages, mail or similar.

Back up. You can’t save your existing back up you will have to start a new one once you have set up your new Apple ID.

Keychain. You will be given the opportunity to save passwords and credit cards to your device when you disable this service, merge them when prompted when you re-enable the service after signing into your new Apple ID.