Yep, there are vit.D3 drops with K2 included now and I take those.I don't think so. You can google it yourself I guess. Here it says 4k/day for adults, it is for the US https://ods.od.nih.gov/factsheets/VitaminD-Consumer/ I know there is research saying more is safe as well, but I'm telling you what the "official" recommendations/limits are.
Interesting! Are you supplementing K2 at the same time as well? Of course if you regularly check your serum levels with good results, it seems to work perfectly for you!