I like animals. Especially armadillos. I know they are native to the Americas.  Do they make good pets?  
I've never heard of that animal. Are they a carnivore or a herbivore?
I'm not sure of their diet.  But I suspect they are either herbivore or omnivore. They are identified as mammals. 
Are they an endangered species as I've never seen one?
I don't have any specific details if they are endangered or not but I highly suspect they are not endangered. As they are a prominent animal that is seen everywhere. 
Are they a big mammal and how long do they live for?
Armadillos are not big at all.  The ones I've seen are about the same size as a house cat.  I do not know how long they live for though.