I see that its a little too much for an inexperienced noob like me, but ill give it a shot :bouncy:
I want to start off with Katon.
As for strengths, as an element it is superior to wind, as that the flames eat up the air sent by the opposing forces. For weakness, it is week against water, cuz thats pretty logical (dont know what to say here, really ), it cools it down.
As for people, we can put the whole Uchiha Clan there, with Saratubi Hiruzen, and Asuma( i think its the whole clan too that does this), Mei Terumi, and Jiraiya are the ones i remember, Konoha is seen to use the element most often, and as for KKG, Blaze release, Boil release, and Lava release are all used in conjunction with Katon.
Thats all i can say, is it any good ?