after importing a midi file for drums how would I replace the midi for say the snare or base drum with a real drum sample is the a way to import the sample hit in to the piano roll and somehow change every midi drum hit for the snare or kick to the new sample??

one way you could do this is to drag the midi file into a piano roll on a 'Layer' channel.
Then set up your drum hits in samplers. Set the samplers as children of the layer. In the 'misc' section of the sampler, you can set up keyzones on the keyboard. Also set the root note to the midi note in the piano roll.
If you set up your drum samplers in order of note, and make sure that the midi is chromatic, then you can use the 'split children' function to automatically set up the keyzones on the samplers.

Use a drum machine like Battery. Drop the midi file right on the battery sequencer track, then load all the drums into battery. Battery can load all drums in one swipe instead of one at a time. This is how I do beat slicing in FL Studio. I use BeatCreator to chop up a loop, then export from BeatCreator as a sf2/midi combination. Then I load the sf2 into Battery and drag the midi file on the Battery channel in FL and I'm done. I can either play it back the same, or go in and rearrange all the drum parts to make a completely new beat.

cool thanks guys Im going to try it right now.