Regarding the changes to the penalty for abandoning duty, I think it just means the penalty now applies only to the first person to abandon a duty after it has begun*, and not subsequent deserter(s).

If I'm not mistaken, currently, if someone else leaves a duty first, and then you decide to leave as well, but a replacement was found and thus returning the party to full status before you leave, you will also get penalized. Now, that won't be the case any more. As soon as someone leaves after the duty began*, you can leave without penalty.

*What determines when a duty begins is another matter. It's probably just when the instance itself begins, but it could also count each separate pull as separate starting points.