I agree that at 6 weeks she shouldn't even be away from her mom, that said she is still well in the age to crop, tails need to be done within 3 days, ears up to 12 weeks! Although I'd say 8-10 weeks is best. Whether to crop or not is a personal choice, and in my opinion has no health benefit either way, it's just what one person prefers.
I have two danes currently, a 9 year old cropped male, and a 6 year old natural female. Iris is my first natural eared dane, she's also my first female, I just thought the natural ears look more feminine. In my experience the cropped ears get waaaay dirtier! So far Iris has never had an ear infection (and she LOVES to swim), Havoc has also never had an ear infection. Can't say how it may affect hearing since Iris is deaf (not because of her natural ears), but I really don't think that is right.
If I get another dane I don't know if I will crop or not, I'm not going to say I will or I won't. Some breeds I like the look better cropped some I don't. W/ danes I can go either way.