If you are using a third-party email address as your Apple ID, you may need to change it if you are losing that email address or plan to move on to another email service. Apple has a page that spells out the steps needed to change which email address is used as your Apple ID.
The new Photos app for Mac allows you to store all of your photos on Apple's servers as part of their iCloud service. This makes your entire Photos library available on all of your Apple devices including Macs, iPads and iPhones. You can add, edit or delete photos on any device and see the changes on all of them. You can choose to store original photo files on a device, or have the device only use optimized versions of the photos. You can also view your Photo Library on iCloud.com.