Josh, I use the wax. Walosi, the tung-oil-master, says Johnson's paste wax like one would use for wodden flooring works well. I use something made for furniature that appears to be wax flakes moistened with orange oil.
You can always use steel-wool to remove the wax coating and apply more tung oil later. Any residual wax seems to blend in, or get removed by the polishing steps.
Not slippery at all, actually a little tacky. People wax surfboards for grip. And skis for grip and glide. Depends on the different waxes and the temperature. I guess it's possible to be more slippery with some cloth gloves in cold weather though. I like the idea of the easily removable wax getting dirt ground into it instead of the oil. I like to checker or carve the wide ring in the handle to increase the grippiness anyway--like is done on the chitlangi or some of the older khuks shown in the FAQ.