Deadlift grip on the bar: My personal preference for all my clients is to go with a double overhand grip until their grip becomes the limiting factor, which usually isn’t the case until we get into the 1-3 rep range and then we can go to a mixed grip. I think too many people go to a mixed grip too early (even in their warmups) which I find limits their grip development and develops some bad alignment habits. And wraps? I can’t remember the last time I’ve used them for something other than helping rack a Front Squat. If you can’t hold it, you probably shouldn’t be lifting it.
Now, some of these positions don’t necessarily apply for Powerlifting, but that is a sport in itself. The question is as always, “Are you deadlifting to get better at deadlifting or deadlifting to just get better???”