Alright, for you base to keep the heart of fire contained you must line your moat with firebrick which is decently expensive but I was able to get some from a asphalt plant and they seemed to work great for our purpose, "which was just melting the metal heh" but im sure if done correctly would of been fine. I would get fire bricks build a trough so were you can put the meal in and let the flames devour it to its purer form for you to shape it.
The whole blower with the leather is a pretty old idea and works fine its just you can do it alot easier and with less work if you use just use proper ducting/fan so they don't melt after an hour or so. "I failed first time heh" I used a cheap forge blower I got off craigslist thankfully and set it up without much hassle. I was reading on this site
and they have blueprints for ALL that you need and explain how to make them out of washing machine fans ect... have to register but only takes a sec.