Will factory reset of my old iPad2 remove my transferred data from the new iPad and iPhone? Everything's on the same account. Do I have to unsynch first?
If you factory reset your iPad, you won't wipe the data from your other devices.
To give you some perspective, it would be counter intuitive if you lost your phone and remotely wiped your device only to have all your other devices wiped as well.
That being said.... don't have the expectation that your other devices are back ups of your data. While you will have access to your data in the case of losing a device, if you inadvertently delete your data (all your photos as an example) that change will propagate to all your other devices.