"This morning we saw lots of little black tadpoles swimming around in the puddle and my kids wanted to collect some. I am worried that there may be diseases that they can carry either in the water or that they may grow into some type of dangerous toad or frog. Is there any way to know how safe these are to bring into my home? I have 2 young kids and I am pregnant as well, hence my concern."
Most diseases/bacteria/viruses/parasites are species-specific which means that only that species or related species gets it. There are few things you can catch from a tadpole. In fact, I can't think of any except maybe a bacterial infection in very rare cases. If you wash you hands after working with them, there is basically no risk. I swim around with my pond animals and put my hands in water with tadpoles all the time and am still fine. I do this even with cuts but for kids and yourself, wear gloves if you have cuts on your hands.
"I read something about a dangerous Australian toad (on the internet) but I am assuming they are only in Australia. Please pardon my extreme ignorance. I woul love to raise these tadpoles into frogs and see my kids learn about them but 1st want to be 100% sure this is safe."
Where do you live? The cane or marine toad was introduced to Australia but also now is in Florida and parts of Texas. It is toxic. Otherwise, native US frogs are not toxic and toads (as adults only) are very mildly toxic (not deadly, just irritating).
As for raising tadpoles, see
http://www.fishpondinfo.com/frog3.htm