Had the card for about 9 months. So far so good.
I believe there's a 60k pts earn limit per year, but anecdotally I've heard this is not enforced, at least not by software. I think it takes a human to notice abnormal spend on your account. Not 100% on that.
Additional fee- none I remember. There's a 10k per transfer minimum of pts, and transfers are only possible in 10k blocks.
I've never tried adding more $$ to the account than necessary, as they gave me a stupidly high credit limit.