What's up PRiZ.
There is a myriad of ways to connect your equipment.
It depends on what you have and/or what you are planning to buy.
It also depends on what is the best configuration for you and the way you produce.
Now, I will not try to confuse you (I read your first post on this BBS).
Let's take the first thing you mentioned...Connecting a keyboard.
You could, for starters, go out of your analogue 1/4" outputs into your sound card, or you could go out of your MIDI outputs into your soundcards MIDI inputs, or you could out of your computer's MIDI OUT then THRU your keyboard into another device, or you could go out of the LIGHT PIPE device on your keyboard into your sound card etc...
The people here on this site will help you to make the correct decision.
You might want to tell us exactly what kind of music you will be making.
You should also share with us how much money you are willing to spend on equipment.
I have my equipment setup like this (keep in mind that I have 3 soundcards)...
Amp>Monitors
Board>Amp
Keyboard >Board
MPC>Board
Turntables/Mixer>Board
Board>Computer
That is the"simplest" way for to connect my equipment.
My board gives me 8 analogue INS/10 digital INS, 10 digital OUTS, and 2 MIDI INS/OUTS.
Sound card #1 gives me 8 TDIF (digital) INS/OUTS, 2 SPDIF (digital), and 2 MIDI INS/OUTS.
Sound card #2 gives me 4 analogue INS/OUTS and one SPDIF (digital).
Sound card #3 gives me 1 stereo IN/OUT.
I also have 2 additonal MIDI IN/OUT, by using
a Midisport 2X2.
I hope that helps a bit...
spin