Good questions Kristina,
If your bird eats a good healthy diet, the chances of her becoming eggbound are much less than a bird who is a seed junkie. Egg laying without a mate is more common in smaller birds such as cockatiels although I wouldn't say that Amazons don't ever do it by any means. Again, it is usually the smaller birds who have more problems with being eggbound also - with or without a mate. It may be because the smaller birds are more apt to be the ones who eat seed as the major part of their diet.
I don't think that a male of another species would cause egg laying but again - just because there is no male of her own kind in the house, you can't be guaranteed that she will never try to lay an egg.
My African Grey, Jewel will be 6 years old in July and even though there has been a male CAG in the house for the last 2 years, she has never laid an egg. Of course at 6 - she is still a young bird as is your Amazon at 2 years old.
