Not sure what you mean by "use my piano as something like an MAudio midi controller"; but it has both a standard set of MIDI In/Out/Thru ports and a USB/MIDI connection to your computer, so it certainly has the potential - unless you're looking to use it to control your choice of DAW software (which it might not do). From my personal perspective, Cubase (which apparently comes bundled if you bought the CP5 new) is overkill for a newcomer to this stuff - and it costs a TON to upgrade!.
Here's what I use for my home studio recording: 1) Anvil Studio - to compose/program MIDI tracks 2) Multitrack Studio - to do all of the audio mixing and post-processing (FX). Both are 'free' (for the 'lite' versions, of course) and very cost effective to upgrade to whatever level you need. I can also recommend both of these from a support standpoint, Tom at Willow Software (Anvil Studio) and Giel at Bremmer Audio Designs (Multitrack Studio) are fantastic at 'real-time' support. It's never taken more than 24 hours to get an answer if I needed something (like instrument definitions, etc.).
You will need a couple of standard MIDI cables and a MIDI interface. I recommend you get an M-Audio MIDISport, either the '1x1' version (one port) if you only have the one keyboard, or the '2x2' version if you want the potential to expand. You can also opt to just use the USB/MIDI that's built in to the CP5, and get yourself the appropriate cable. You will need the Yamaha drivers for that interface. I have a Yamaha MM6 in my studio, and use the USB/MIDI for 'driving' the MM6 with a DAW sequencer. Works very well.
Feel free to post additional questions. Gary and I don't always agree; but we're always willing to offer advice.
