1st off, for recording I would steer away from Behringer. They generally have noisy preamps. Also, if you are going for a board, ones with built in effects usually have mediocre built in effects. If you are using it for live sound it might be ok but its not worth the extra money if you are just using it for recording.
As per DI boxes they are used to connect unbalanced instruments to balanced inputs.. ie. A keyboard (1/4" outputs) to a mixer (XLR inputs). Balanced cable generally has less noise in longer runs than unbalanced.
Oh yeah, what are you recording where you need 16 inputs? (just going off the stereotype of this board)
