I got into forging and smelting as a teenager but once I left for college I dropped it. I still have a melting furnace I built from a 10-gallon drum that I hope to convert into a gas forge for knifemaking. I was looking to use gas this time since it seems much cleaner, faster, and more hobbyist-friendly (I may only get to forge a couple hours through the week and on weekends).

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I see pre-made forges aimed at knifemakers on Etsy and Ebay are available. I had a few questions about all this.

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So I wonder:

1. Could the small pre-made furnaces like this work well for knife making? Has anyone had direct experience with similar models? Could reach forge-welding temperatures? https://www.ebay.com/itm/Propane-Forge-Knife-Making-Blacksmith-Gas-Forge-Farriers-Furnace-HF2-U-S-A-/142722160084
2. Most of the forges I see are somewhat small, with only 1-1.5" of insulation and a thin firebrick inside like the one above. Would it be better to use a larger shell (10-gallon Drum) with more wool/insulation to provide a similar interior volume with more heat retention?
3. I see people having a lot of trouble making their burners. Is there a solid recommendation for a premade burner or two I could use with a DIY forge?
4. How much gas would I be using? I have 2x 100lb. LP tanks I could use, it seems to cost about $80-90 to fill one of them where I live. If I forge say 10hrs. a week on average, heating pieces of 1084/1095 up to 12"x3"x.25" to forging temp, how often would I be looking at refilling them?
5. What are the recommended resources for forging knives out there on the net? I'd appreciate all the help I can get!