Lots of great information above, I have used paper, but prefer the speed up in my cook times I get using foil. As far as the bark, just simply open the foil during the venting phase and your bark will reset, otherwise, yes, foiling will soften up the bark.
As far as the rest, the longer the better, you should allow the meat to naturally cool down, preferably reaching an IT of 160 or below prior to slicing to prevent to much moisture loss. This allows the meat which was under stress during the cook process to relax and redistribute its natural juices throughout the muscles, not all towards the surface, which is why you will have excess juice when slicing hot.
As far as tenderness, if you have had a piece of brisket that was not tender, in my experience, you didn't cook it long enough. Anything that is cooked long enough (with some sort of wrap) will get tender (Select, Choice or Prime grades). The big differences between the grades of meat is more the mouth feel or chew that a piece of meat has. The better the grade, the better the internal marbling, the better the mouth feel, this is what gives you the "melt in your mouth" feel that we all love. Selects will rarely get this good, you can get them tender, just not butter tender. Choices are better, but you still stand a chance of getting a not so good Choice (due to the way beef is graded). Prime or Waygu is an almost guaranteed melt in your mouth feel when cooked right.
I know that most preach that anything above 205 is just good for chopped or pulled meat, but I strongly disagree. I cook all my briskets to toothpick tenderness (when the round toothpick slides in the middle of the flat with little to no resistance), not worrying about IT, but for grins and giggles I usually check them when I pull them, 99% of the time, they are above 210. I always slice my flats (for competition or at home) and yes, some of the slices don't hold up, but it is some really good eating.
The biggest key is patience when cooking a brisket, it's done when it's done. Use the IT as a benchmark, when to wrap, when to start probing for doneness, etc., but don't pull that brisket from the heat until it is probe tender, you won't be sorry!