Need help to get ready for baby keets!?

So i found two eggs in my female parakeets nesting box yesterday and found three today! I'm not sure if they're fertile but I'm not gunna take any chances. They are at least one year old and she he's a little male playmate. I wanna do all I can do to help. There's one banana mineral thing, one white cuttlebone like perch thing, veggies and fruit fed to them regularly and conditioning supplement seed for stressful times mixed in with theyre regular diet. What else can i do to help the outcome of healthy SURVIVING newborn baby parakeets hatching out of those three lil eggs? The female has been sitting on them almost 24/7. And how could i find out if theyre fertile or not? Is there a way? And i keep the room mildly hot most of the time. Will that help any?