The fore plane is a traditional English tool used to get rough boards fairly flat so that you can then make them really flat with a jointer plane and ready to finish with a smoothing plane, scrapers and (sometimes) sandpaper.
Fore planes are supposed to be about 14″ to 18″ long. If you want to use an old metal plane as a fore plane, a No. 5 jack plane or No. 6 fore plane would be a good choice. I use a Hock Tools A2-steel replacement blade in my fore plane. A2 is a little harder to sharpen for me, but this modern steel takes a heck of a beating before it gives up, so it’s perfect for a fore plane. I also have a couple wooden-bodied fore planes that are nice because their light weight makes them less tiring to use.
Fore planes are supposed to have a curved cutting edge and are used directly across and diagonal to the grain of your board.