Basically Killa Kan is smaller version of Ork Dreadnough, usually deployed in squads of 3. The machine is piloted by Grots - because normal Orks are not very good with all that switches and cranks. Armament varies, but always consists of one melee weapon (Power claw, saw) and one ranged (Flamer, Rokkit Launcher, Big Shoota). This Killa Kan uses Power Claw & Big Shoota configuration, which is possibly the most common one.
This is how original Games Workshop's model looks like:
We actually have a link to your other W40K models on the Tau 40k forum I am a member of. I have been impressed with your other work and I'm similarly impressed with your newest creation. Keep up the good work, I think it looks great. Have you ever thought of fielding a whole 40k army of just Legos? :-)