請問一下 我如果一隻iPad原本有一個ID 然後在新增一個ID的話 我登入新的ID 那舊ID的照片及下載的App 會出現在新ID裡嗎？

They may not be removed. But you will not be able to access them definitely.

For example:

1. If photos are not stored locally, but iCloud, you will not be able to access them once the ID has changed.

2. App, especially paid App, may connect to Apple's server to verify the ownership.