A. There is no upgrade price unless you bought the older iLife (or you bought a Mac with the older iLife) after the newer version was released. And that too is a limited time offer (I do not know when it ends, or if it is still in effect). Check with Apple Support for availability and price.
GarageBand from Apple Computer uses audio loops and MIDI loops in Apple Loops format. It can work with Audio Units plug-ins. Apple Macintosh Compatible FireWire and USB interfaces can be used to connect Audio and MIDI instruments to your Mac, and be recorded into GarageBand.
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