I don't use any swivel or anything...just tie a hook straight on. The way I fish it, I don't get much twist in my line. This is probably because I am not casting a long ways with this bait, I fish it primarily in and around cover. Hooks with these can be interesting, I personally haven't been in one area long enough that the wacky rig was all I needed, so I would end up switching back and forth on how it was rigged, retying would take too long, so I just started throwing a wacky rig on an EWG hook. I haven't noticed any difference in the number of strikes, and the strike to hook-up ratio is high with a big exposed hook. Rarely will you see me with anything but a 5/o hook tied on with the senko.
I normally do not like throwing a wacky rig with anything under a 6" senko, I just don't have the patience to sit there and wait for it to sink, I prefer the 7" wacky rigged. The big benefit I see with the 7" is that the senko is heavy enough to pull the line down through cover, where as the smaller baits don't have the weight, so the bait ends up hanging up too often, and you won't get nearly as many strikes.

-- Josh