Download a Live CD, and see how it goes. I don't know about Slackware, but I know Ubuntu has live CDs. Look and see if there's gonna be any major hardware issues. If there is, search out the answers. Once your satisfied you should be able to get a workable system, dual boot Windows and Ubuntu for a while, and test out the various things you want to do, if it all works out. I'd recommend a minimum of 1mo dual booting. Don't think cuz all is well after 2 days, you're ready. If after a month, you're comfortable with the applications in Linux, that it detects all your hardware, does what you want, etc... then do a clean install and blow away windows. You'd have to be crazy to jump feet first into Linux, w/o at least exploring any hardware/software issues.
I'd say most people who make a successful transition, generally follow a path similar to above. Just jumping in, removing Windows, and "winging it" so to speak, almost always results in frustration and simply reinstalling Windows. I know this, because I've been there..
The last part you're kinda putting the cart before the horse, but boot a Live CD, open a terminal and type "man cli" no quotes. Its got a lot of info about a lot of switches in cli