Q: I want to use iCloud Photo Library, but before I turn it on I get a message that my photos will be removed.....I won't lose any photos that are on my iPad will I?

Any photos that you have synced to the iPad by using iTunes will be deleted from the iPad if you turn on iCloud Photo Library on that iPad.

If you have the original copies of those photos on the computer that you used to do the sync via iTunes, the following instructions from Get help with your iCloud Photo Library - Apple Support may help or you could manually upload the photos from the computer to the Photos app at https://www.icloud.com/ and they would then automatically download to your iPad if you have iCloud Photo Library turned on.

iCloud Photo Library doesn't upload photos and videos you copy to your device from iTunes. To upload the original versions, follow the steps below.

OS X Yosemite 10.10.3 or later

To upload original versions of your Mac library, click Photos > Preferences and turn on iCloud Photo Library.

You can also use AirDrop to copy the photos from your computer to your iPhone, iPad, or iPod touch:

1. Make sure that you're signed in with the same Apple ID on your computer and iOS device.
2. Unlock your iOS device and turn on AirDrop.
3. Open a new Finder window on your Mac and choose AirDrop in the sidebar.
4. Drag the photos to the icon for the iOS device in the Finder window.

Windows 8 or later

If you're using a PC, follow these steps to upload photos and videos to iCloud Photo Library:

1. Go to the Start screen.
2. Click All Programs.
3. Go to iCloud > iCloud Photos.
4. Select Upload photos and videos.
5. Select the photos you want to upload.

Get help with iCloud Photo Library for your Windows PC.

I want to turn on iCloud Photo Library on my old ipad3 but get the message that photos will be removed. I want to make sure I won't loose any of my photos if it turn it on.

Are photos on your iPad 3 that have been synced to the iPad using iTunes?  All iTunes synced photos will be removed, when you enable iCloud Photo Library. Did you save all photos from your iPads to a computer? Be sure to save the photos to a different device before you enable iCloud Photo Library.

It depends.

If you have any photos on it that are in your photo stream album but not in your camera roll you will lose them (they are probably on another device in this case but you should make sure and move them to your camera roll if necessary). You will also lose photos that have been synced via iTunes if you have any, but again they should be in your library on a computer if you've synced them through iTunes, but again it's worth checking.