Lump charcoal is in the chute. You light it at the bottom at the grate, the heat travels up to the oven throught the oven inlet. Coal cannot burn up the chute because the top lid is airtight. Gravity feeds new lump to the fire and the ash falls through the grate to the ash pan. Heat is controlled with the valve (air). one characteristic of this type smoker is a completely mind blowing cook time, hands off. there is a forum dedicated completely to this type of clone. i don't know if you guys post other forum info or not.
Not much is needed to keep the lump in the chute, out of the oven. The "where do you add wood" question is a 3 page debate elswhere, but suffice it to say, scattered in the lump chute or in the ash pan as desired, will work, just personal preference. Just keep in mind, that my oven is oversize in relation to the real deal. Lots of mods needed for my monster roto.
Considering the setup you have which.......by the way, I think is awesome. That charcoal tower would work really well with a guru---I am thinking that it truly would be a set it and forget---just go to bed and wake up to briskets!!