I would work this back in reverse... meaning the actual physical import of the coffee into the USA is probably the very least of your worries. Johns link does cover most of the FDA requirements. You need to register your facility at origin (the warehouse) as well as registering yourself in the USA. This helps streamline clearance. US Customs are fairly fanatical about taking samples...every shipment we send into the USA has at least 12 samples taken from it. I guess this is to varify that fumigation and/or the phyotosanitary certification is correct. Docs you need are (in no particular order)> the OBL from the shipping line, the Invoice, packing list, Phyotosanitary Certificate, ICO Certificate, FDA prior notification (fill out EVERY shipment online). You also need to make sure you correctly line the shipping container you use with card...and check the container prior to loading to make sure the last shipper did not use it for motor parts!!!!!
But... this above is as I mentioned the easy part.
The area I would be concerned about is either end of the shipping. You need to really know coffee to be successful in this part of the trade. (If you are buying avergae greens you are going to be just another broker trying to make a buck$$. You need to be able to offer unique, rare ande/or unusual coffees that attract a premium. To do this really, in all honesty, would require you spending a lot of time at origin sourcing yourself. This, I reckon, is key
Then of course the other end of the equation is being able to get what you have to roasters. You will have the problems mentioned above, especially if you select poor quality containers, poor trans-shipping schedules, lower quality facilities at origin where 'stuffing' a container can go badly wrong and lead to mould/mildew and other humidity damage.
Good luck with this....