Connecting a dynamic microphone to a computer is a straightforward process. You just need a couple pieces of gear.
Exporting MIDI from Garageband, while not technically possible, can be done with an .aif to MIDI converter. Read this article to learn more.
EQing a nylon string guitar isn't all that different from a regular steel-string acoustic, but there are some differences.
Pitching your vocals in Garageband is fairly easy to do, and it can be accomplished in a couple different ways.
How to pan guitars in the mix, whether it's rock, jazz, or another genre.
If your guitars don't sound as good as you want them too, this article explores some tactics you can try out.