A. GarageBand can record 8 Audio tracks and 1 MIDI track at a time
Theoretically GarageBand can handle 255 Audio tracks/64 MIDI tracks in total (I assume that's basically an "OR" with some combination in the middle, but I've never tested that) in a single project.
I've worked with two projects that each had 54 tracks in them.
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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