slaves expand your max. carry capacity and can be sold for good profit in slaver towns... (but give you slaver reputation which might tip you towards the Federation path)
when you purchase 2 x3 bonus multipliers, the overall bonus should be 9x not 6x. That's just basic arithmetic and it should have been clarified if your intention was to treat it linearly...
 "Caravaneer 2"){kind=icon}
 "AdVenture Capitalist"){kind=icon}