Heres how you need to cable it.
MPC MIDI OUT to COMPUTER MIDI IN (both ports if you want 32 channels (but you need a MIDI interface with more than one port))
KEYSTATION midi out to MPC MIDI IN
TURNTABLE to PROFIRE (line inputs...)
On the track on your MPC set it to MIDI and then define what channel and what port (1a 2a, etc..)
You already said you watched my video but you should also get the template for logic http://briandelizza.com/Articles/articles.html
The gist of how that template works is it takes your MPCs MIDI signal (all 16 channels) and splits it into the individual channels. Each channel is connected to a channel strip in logic. So when you send MIDI on channel 1 from your MPC it goes to the first channel strip. The MPC (at least the 2000xl) has 2 ports which will allow you to use a total of 32 different instruments.
The Keystation needs to be routed THROUGH the MPC. Reason being is you are sequencing your MIDI info in the MPC and not in logic. In fact, most of the time logic will not be playing at all (unless you are syncing it with MIDI Beat Clock, but worry about that after you get this setup)
EXS is not the graetest sampler FOR WORKING LIKE THE MPC (i'm not saying its a bad sampler, but you can't work as fast as with a MPC)
I would HIGHLY recommend buying the plug-in phatmatik, it allows you to bring in a sample, chop it in seconds, and automatically map it to your keyboard. Not only that but each slice can have its own parameters (EQ, ENVELOPE. FX. etc..)
save your self the headache and buy it, after you use it you wont go back to anything else (again assuming you want it to function like the guts of an MPC with the convenience of software.)
are you talking about MIDI or audio?