Accuracy, Crit Chance and Status damage are pretty easy to test. From the looks of it, Accuracy seems to be boosted by 20-30% (take a low accurate gun, use Seein Red, measure the decrease of potential bullet spread), so I would assume that the other values would be in that range as well.
€: Accuracy reduction for me 15 seconds with Death Follows close and 8 seconds without, so it does get the 7 seconds from Death Follows Close and I assume it would also get the efficiency boost.