Connecting a condenser microphone to your computer is done through an audio interface with phantom power, or via USB cable if you're using a USB Condenser Mic
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.
The Focusrite Scarlett 2i2 (3rd Gen), in my opinion, is the best audio interface for beginners to home recording.
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.