1.- Of course, since it is already in Official KL WebSite, more official than that is impossible
2.- Sometimes, and probably when uninstall previous versions of Kaspersky, KL Root Certificate usually is not deleted and duplicates are kept in Windows Manger for certificates, and in FireFox own manager. Those duplicates should be removed and keep the one from last version.
3.- Probably because infrastructure to buy KSC data traffic is not available yet... about license of HSS working in KSC, I'm not sure, I guess will not work, anyway try and let us know