That XR12 looks interesting and might fit the bill. I was going to suggest a digital mixer. My son in law worked at a church that was cutting edge on audio and lights. They had iPads that would allow them to walk around the sanctuary and make changes as needed to the sound and the lights. Very handy when working with large rooms but I can also see where this might work for what you're wanting. The XR12 is waaaaay more affordable than the digital mixers I'm referring to that the church was using.

To answer your other question ( hope I understood this one correctly )

....how do I connect a keyboard for when I want to record something live using its internal sounds and not simply midi over USB?

You would treat it like any other audio source. Some of the guys using Sonar actually record the keyboard as midi and then send the midi to the external keyboard and allow it's internal sounds to be used and capture the sounds as audio because they love the internal sounds better than samples.

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