The Fitzgerald had to change course because of the waves, they wouldn't have wanted the waves, coming out of the north, on their port side. Taconite pellets (partly processed iron ore) can shift in the holds, and if part of the cargo moves and the other doesn't on a 1000 foot ore boat it could twist the hull (that may have actually contributed to the breakup, it's unknown). They knew they were near Whitefish Bay, but needed to head into the storm for stability.
how much profit is there in operating 10 sailing ships than a single New Panamax ship?
Depends on crewing and the availability of customers who aren't in a hurry for delivery. One savings over a Panamax right off the top is the 40,000 or more gallons of fuel that it won't be burning every day. Another is that these ships apparently are exceedingly automated (in part because that's the only way to deal with sails that size), if they can reduce the crew size so that they're only paying 10% as many crew per ship as the Panamax it's break-even.