You can then save these photos to your camera roll on your iPad and delete the shared stream (or just leave things the way they are). (You don't have to invite any subscribers, as the owner of the shared stream you are automatically subscribed to it.) The shared stream will then appear on your iPad in the Shared section of the Photos app. If you want to stream older photos from your iPhone to your iPad, you'll have to add them to a shared stream as explained here.

(If it says Install rather than Remove, click Install then click Apply at the bottom to install it.) Then go back to the Apps tab and click Install, then click Apply at the bottom to sync again to sync it back to your iPad. This will remove the app if it's present. Then you can connect your iPad to your computer, open iTunes, click on the name of your iPad in iTunes, go to the Apps tab and click Remove if it this is shown next to the Gmail app, then click Apply at the bottom to sync your iPad. This will transfer the Gmail app to your iTunes library if it's not already there. One thing you might try is to connect your phone to your computer, open iTunes, then go to File>Devices>Transfer Purchases.