Regarding 'stays in the book'-how long it has to stay to be considered a "maker", i wonder?
As long as your order doesn't land on an existing matching one, you're a maker. Even 1ms is fine. The distinction is if you pick an existing order and fill it (possibly only in part), you're a taker. Otherwise, you're a maker.
Regarddless of that, even 0.6% maker fee is outrageously high, imho, especially if you compare it it to what happens at the stock market.
I a gree it's pricey.