You really need to search the web for some sites and some background on exactly what you want to do. I hope you do more than look here before you get anything.
Try starting with http://www.backyardmetalcasting.com/index.html
You will not be melting steel. You will not even touch titanium. Depending upon what you build you might be able to melt small amounts of brass. The most likely is aluminum. Iron is most likely a no unless you build a cupola or get some really kick ass refractory and one hell of a burner.