When u think of filtering noise from EEG signals, you have identify what all kind of disturbances are present in your EEG . EEG may contain artifacts like ECG noise, eye blink noise, jaw glitches and even AC line frequency. So a single type of filtering method will not work for all kind of noises. Think and read more about that.
For classifying epileptic EEG signals many methods are being used now. The most crude method is to use frequency component as a feature for classification. There are other methods like Spike detection analysis. There is a lot of literature available on the net. Do some more googling , you will find many.