I own a BR864.
If you want to transfer basic tracks for remixing on a PC, look elsewhere. The transfer over USB is designed for transferring final stereo mixes. It takes a long time to do it track by track (you can not do all tracks at once) because the conversion into WAV is done on the 864 itself and takes about as long as it does to play the track (the actual time to transfer over the USB connection is short by comparison).
So for a 4 minute song if you use all 8 tracks it will take over half an hour to transfer all 8 because it has to do 8 WAV conversions.
My feeling is if you plan to mix on a PC, then just record on the PC. I mix and master on the 864 so I only do a single transfer, that works great for me.
As far as your other question factory resealed is better than dealer resealed because the former means that the unit was fully checked out before being reboxed, but both are good ways to save some money as long as you get the full factory warranty.