1. What main staple diet should I convert Noel over to she is currently been eating the stuff the breeder gave her which is harts brand cockatiel food. It dosn't seem like enough.
I suggest the staple part of a tiels diet is a good quality seed mix (look for a clean, dust-free mix with a large variety of seeds in it) with pellets offered either mixed in or in a separate bowl.
2. What fruits are safe if any??
Most fruits are safe. Avoid the seeds though, especially apple seeds as these are actually toxic. My tiels aren't fruit eaters, but one of my budgies is nuts for nectarine, banana, honey dew melon, rock melon and apple. These are all good things to try, but don't worry too much if your tiel doesn't have a sweet tooth and turns her beak up at fruit.
3. What veggies are safe also is frozen thawed out ok??
Again, most veggies are safe and yes, it's fine to freeze and then thaw to feed or even just use shop bought frozen veggies (fresh taste better though, hehe). My guys like carrot, broccoli, bok choy, spinach, peas, corn, etc. Dark leafy veggies are usually the best for them.
Specific bird treats like millet sprays and seed treats are ok occasionally, same with things like a little bit of peanut butter on a wholemeal cracker.
5. Any other types of food safe for them??
Yes, lots! Whole grain breads, pasta and rice are all good options. I like to always have some brown rice with veggies and/or lentils cooked and frozen in ice cube sized portions in the freezer ready to thaw and feed. Legumes like lentils and beans are good sources of protein. Unsalted nuts (peanuts, cashews, almonds) can be fed occasionally. Another good food is hard boiled egg. You can mash it up (shell and all) and mix in some chopped or grated veggies to feed. My guys love it.
Generally speaking if it's good for you, it's good for our birdies. You want to avoid things that are fatty, salty or sugary.