Having the charger get [very] hot is normal behavior for a charger. It's it's function - to convert the power from the mains to something the iPad can use to charge. That conversion uses energy, which is dissipated by giving off heat.
As far as it not charging the iPad fast, (1) make sure you are using the iPad charger AND that you are plugging the charger into the wall outlet, not the computer's USB ports. Most computers don't put out as much wattage. And, while an iPhone/iPod charger will work, they will be much slower as they don't provide as much "juice." The iPhone charger puts out 5 watts, while the iPad charger puts out 10 watts.
Or, (2) when you are talking about the iPad3, then it's going to take much long to charge it than either of the other two iPads. The battery is so much bigger, so it will take more time to charge. Again, this is normal...even with an iPad charger plugged into the wall.
Hope some of this clarifies.
Marilyn