1) I have a MacBook Pro that I use for all my music software. I use a combination of Logic Studio, ProTools LE, Melodyne, Garritan Live Orchestra, and some live recording (also through Logic and ProTools). There are also many music packages that come with Logic Studio and ProTools (like Reason, Amplitude, Trash, iZotope) that I also use for specific instruments. Trash is a great program for manipulating (and bringing to life) drum sounds, iZotope is a wonderful mastering program, etc...
Logic Studio comes with a bundle of stuff (pretty much the upgraded version of garageband). It's a set of about 7 DVD's of content, and is well worth the money. Not too expensive compared to what other programs (like ProTools) cost, but you can pretty much do everything with that.
ProTools is excellent for live recording and editing, and that's why I use it. I have a really nice Neumann Microphone that plugs into a Focusrite ISA One Pre-amp. That then plugs into the ProTools Digirack 003, which plugs into the computer.
Also have a pretty basic (OLD) Yamaha PF85, that has very limited live sounds, but has midi capabilities. So, I plug that into the digirack as well and use most of the midi sounds from Logic.
The live recording is mostly done on the microphone (aka vocals, sound effects, etc.). Then they're manipulated on ProTools using different effects that come with the program.
2) The best advice (and I hope you don't feel like this is cheap) is to get some kind of DAW software, and just play around. I have a couple friends who use Fruity Loops, and can make some insanely good beats for hip-hop. Some of those guys are really good at it, and can produce some high-quality stuff.
But, before I went to school to study composition, all I did was just play around with anything I could. I had no concept of what musical notes or notation were. I just sat down on a piano, and tried to figure it out. I would go outside and throw sticks on concrete, and then on clay, and then on grass, and played drums on trash cans, and tried to make music on literally anything I could get my hands on. It's all about experimentation and creativity. Trying new things, new sounds, etc.
A lot of those digital programs will allow you to record different things, and just mess around and see what you come up with.
If you have a chance, check out my facebook music page. I'm about to put up a piece I composed in college. The only thing I used to compose this piece was a sound clip of an audience cheering. Then, I manipulated it using ProTools, and came up with the final product. The piece is called "Invasion" as it's supposed to be an Alien Invasion. Once again, the only sound clip used (and manipulated) is the sound of a crowd cheering.
PS: No, the guitar on the theme is actually a midi guitar sample from Logic. They do good stuff