Again to chime in with Susan...
The Huky is very much a "kit" roaster, which works when ordering a "standard" kit.
I can of course put together an order list for you, but that have been done maybe lots and lots of times already. Look in the "Pre-Purchase" subforum (where you placed this thread) and read up.
Now, if you are looking at the Huky for learning how a gas roaster works, most larger roasters typically uses solid drums.
As pointed out before, some sort of fan controller is good, as the built in damper is too crude for fine contol.
Most of us hooks up the roaster to a laptop and views/logs the roasts with Artisan coffee roasting software, which needs some kind of interface between the ThermoCouplers and the computer. The Center 30X (many versions available) is available from Mr Li, while many of us are more into the Phidget 1048. Or why not go for a Arduino/TC4 solution, to which you later can add functionality as you choose.
The main thing though is to learn the roaster and roasting. That will take some time and give you the experience from which you will most probably find directions to what to modify, if you want to modify anything at all. Personally, I don't mind the fully manual style of roasting, even though I'm building a cyclone exhaust system at the moment. Now, I'm close to 3 years with my Huky and I'm still learning from every new bean I roast.
The reason for me going on about "duplicate", is that unless I can duplicate, I do not have good enough control so that I can tweak my roast to whatever I want to. This is the basis for any roasting on any coffee roaster, so it's nothing Huky-specific.