If the iPad you are using does not have iCloud Photo Library enabled, then anything you do on that iPad will not have any effect on the iCloud Photo Library.
Your questions are starting to make me feel cautious. In the past people have mistaken what iPad they have, and even what version of iOS. To be absolutely certain, go to Settings > Photos (or on new iPads it should be Settings > Camera & Photos). There should be no option to turn on iCloud Photo Library.
Even if your device does have an option to enable iCloud Photo Library, as long as that feature is not turned on, then nothing done on that device will affect iCloud Photo Library. It is a service you have to turn on.
No reason you can't continue to use Photo Stream; as long as you know what it does, and doesn't. It's kind of redundant if all your devices and Mac are on iCloud Photo Library, but if you still want to see new photos appear on the iPad 1, then you'll need to leave it on, both on that device and any other device you're taking photos with.
The way you are talking, I have to guess you have other iOS devices, or a Mac. I can't think of any other way you would have iCloud Photo Library activated.