I'm certainly not the most qualified person to answer your question. My instructor said most modern steels are decent for tool making and to practice on.
It really matters what you plan on making? A candle holder or decorative item about any metal that'll get red hot should do. If you wanna make a samurai sword you'll need specialized metal for that project. But i would think a mower blade would be pretty decent high carbon steel, as it's designed to take some abuse.
Me, i'm gonna get my practice in making simple tools, turn screws, bottle openers, meat forks, etc. Most low carbon metals should work for my projects, if i'm understanding what i'm hearing correctly.
As to the forge, there's a neat video on YouTube about a guy making and using a JABOD forge. That's a Just A Box Of Dirt forge with a vacuum cleaner for a blower (you reverse the hose to make it blow). He built a wooden box, filled it with dirt and rocks and was getting metal to forging heat in no time.
Then he broke it down and packed it away just as fast. Some of the coal turned to coke and he saved that for future use.
I hope that helps.
