Probably the most closely guarded secret is how much is paid. Your guess is as good as anybody's, quite frankly.
The costs incurred are considerable.
There have been numerous investigations in to price rigging by the big players. So much so that some car manufacturers have got into the shipping business themselves out of necessity.
Very true even in the Dry Bulk and Liquids shipping markets (which I know a very little bit about). Nerd point: I noticed the draft reduced very slightly recently and then I thought: D'oh! Consumption of bunkers
Also noticed in another thread that Tesla are now getting into the in-house leasing business. Same deal I guess, if you're doing it in enough quantity it's good business to do it yourself, and can be a great earner in its own right (cough, VWFS, cough).