If the only thing wrong with your appliance is a damaged cord, which usually happens near where it's plugged into the wall, and it is a three-pronged cord, the information above is sufficient to replace the plug. Note that you will need to be able to identify the three wires and the color they represent, which is usually followed in decent power cords (of course, not all of them are decent).

Absolutely, if you aren't confident in your knowledge and don't have someone who can verify your work, don't do it. It's cheaper to throw away any given appliance than it is to throw away your home via an electrical fire. But basic AC electricity isn't that complicated, even if it's more complicated than basic DC electricity.