Formica countertops should be thoroughly cleaned. After waiting 24 hours of no contact with hot food, one should pour boiling water directly from the pot on to the counter and roll a hot metal pipe or similar object to maintain the temperature of the boiling water. As you can gather this is not a simple (or safe) procedure and should only be done by someone with experience if at all.
If the gas range has grates they should be blowtorched or replaced, the glass surface does not come in contact with the food and needs no more than a good cleaning. If you have a smooth glass range where the pot rests directly on the glass, it can not be kashered.