1) Yes, mostly.
2) BPs will end up consuming virtually all the nitrate, Kaldness can end up leaving excess nitrate in the water.
3) Nah, it's a new take on an old school bio media. It;s very popular on large scale ponds.
4) No clue on this
5) Both are not nitrate factories. BPs can get you all the way to zero, in fact it can be harmful because of O2 depletion and total lack of nutrients.
6) Wouldn't use k1 in a reef, live rock achieves this function just fine. BPs are another story, many use them with success for ULNSs.
7) See 6.