You can tile over the brick but only use appropriate fireproof tiles. They are specially treated tiles for just such a purpose. They are not much more expensive and come in a large variety of colors.
You can tile over your brick hearth. You can do this yourself or pay a contractor to do the work for you. If you do it yourself check online for the step by step process. If you use your fireplace be sure and use materiel that are firesafe.
