Ok, if you want to go completely digital you need to find out if Logic has "Audio Delay Compensation" It has Plugin Delay Compensation for sure but Im not sure about ADC. You will need this if you want to monitor your external stuff through the software. I know you can do this with Cubase SX 3....BTW, this feature also allows you to use outboard FX....Its very cool actually.
YOU WILL DEFINITELY NEED: A controler. Trust me on this one. I spent 3 years mixing with a mouse because I thought controlers were rubbish. Seeing as your budget is tight I highly reccomend the Behringer BCF. I can see and hear the scoffing, but believe me FOR THE MONEY this thing is brilliant. At 200 euros your NOT going to find a damn thing even close at that price range. When I went completeley digital I SORELY missed having a console. Teh change nearly destroyed me musically...I kid you not... And beleive it or not, its only a matter of weeks I have been using a controler and already my productivity has increased by about 50% when it comes to the mixing...God only knows why i stuck it out with the mouse for soooo long.
I also think you need to think about all your hardware boxes. Remember your going to be working in a completely different way than you were before. for starters, as much as you think you will need 5 outs from your S950 I dont think you will. Bear in min with each active input and output your causing strain on your processor. Im not sure how fast your CPU is....if its a P4 1.7? I think you will struggle a bit? Anyway, you may not need so many inputs as you think because its simplicity to commit to audio thus freeing up the sampler again.
You would connect your monitors to an amplifier, then coonect the amps inputs directly to the main outputs of your soundcard.
So far you have spent 400 euros on your two controlers. Why not then buy a 12 channel Mackie VLZ mixer and simply plug your hardware in to that. Take the main outs from the mixer and attach them to the first two inputs of your soundcard. You can also plug in your MD recorder, CD player, and your Turntables mixer. This way you have everything plugged in, ready to monitor and record and you havent taxed your systems CPU. Sort of the best of both worlds,
As for the rest of your question Im going to leave that to some one else. You did aska bout ten question there, and Ive got typingisitis now hehe..