Re: early kyu expectations
I don't know but I don't think you need to think of it (or explain it to them) as letting things slide because they're beginners. To me it seems like more a matter of prioritizing and giving people a workable short-term project -- e.g., what do you think are some good next things to think about in their practice? As a student I often find that helpful... So you could concentrate on a few mistakes they are making and get them to practice doing those things right until they begin to understand them and begin to make them a habit, then move on to the next few things....
I think you can do that without either giving them the mistaken impression that everything else they're doing is perfect, nor that they are doing unusally badly either.