OK! I'm finally at a point where I know EXACTLY what I'm doing and need to do in order for this Linux-recording stuff to work. I've learned a lot about sound-recording (in general) which I'm sure will be useful on any platform and also lots about how sound things best work in Linux.
A quick highlight of how things fit together and where the challenges lie...
jackd - This is an incredibly powerful piece of software which allows you to "patch" the output of one program (or physical source) into the input of another. As described above, you can "plug" your guitar into your effects program, and then into a specific track on your recording software. You can also "plug" a drum machine's output into another track and a synth program into a 3rd track. (Hope I'm keeping count correctly

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Problems...
1. INCREDIBLY hard to figure out the first time around. I'm an advanced Linux user/admin, I'd hate to see what a newbie would go through trying to figure this all out!
2. Only supports 1 card at a time. Big problem. This SoundTech LightSnake acts as a soundcard. So, as things stand, I can only record from my cable, or playback something I've already recording. Definitely no monitoring! Huge pain in the ass.
Solution: Alsa (soundcard drivers for linux) supports running 2 cards as 1 virtual card. If I ever get my configuration right, this could work. Although the cards won't be perfectly in-sync, it should be good enough to monitor what I'm playing as I'm recording.
Other than the above issues, I actually love jackd. Powerful bit of software ONCE you figure out all the kinks. (This tends to be the case with Linux software in the beginning. Things usually smooth out once the software gets a bit more mainstream usage.)
ardour - Fantastic recording software! It's modeled on professional software available out there and it confuses the heck out of me but not because it's badly designed, just because i'm new to recording. I finally understand how it works and it's quite powerful. Has nice features like a Click Track and, erm, other stuff I don't understand yet

Can definitely see myself falling in love with this software. I could use something simple like Audacity (and I may yet) but I'd like to see if I can manage with something more pro-orientated. I figure it will be good practise for when I'm working on industry-standard software, later on.
hydrogen - Groovy drum machine. Very easy to use. You create "patterns", which are generally single bars of drumming. And then you string them together to form a "song". Very easy to use. You can click with your mouse or use your keyboard. Sounds are very good. Very authentic, to my untrained ears anyway.
ZynAddSubFX - Virtual synth keyboard goodie. Very cool. Plenty of stuff available in the instrument bank. I can see myself creating great backing tracks with this baby. Some of the sounds are very authentic while others are absolute rubbish. No idea, yet, if it supports instrument-bank files available on the net. Will investigate as time moves on.
Jack Rack - Supposed to be a real-time guitar effects (stack-like) program. Haven't had a chance to test it out yet, thanks to my above issues with jackd. Seems to have a wide range of sounds and tweaking available. Time will tell how good this is. User-interface is crap.
Creox - More or less same thing as Jack Rack but much less versatile. I've actually played with this one before but couldn't get decent performance out of it -- this was before I set up my machine to run with a real-time kernel and before I understood anything about jackd. Will post more after I test this properly.
That pretty much covers everything you'd use in the beginning when recording on Linux. I'll post more once I can actually record and monitor what I'm recording. Will also post links to sites that have been helpful.
Comments on the above?