You realize Muu has a Kekkai Touta right? That's better than the KKG. Also, Darui and Deidara have naturally-learned KKG.
yes, and... maybe
yes, darui has the storm style KG, no arguement there
but i thought dei's tech was a secret iwa tech to put chakra into objects, but the whole mouth-hand thing maybe a kg, its hard to say, unless i read something wrong, or its in the wiki
and i dont know if KT is genetic. muu is onoki's master, it is never said they were related, though they both may have it genetically, and muu taught onoki, or it is something that is very secret and difficult, and maybe able to just be learned. but once again, too little info, or i may be mistaken.