Newbie to home servers....

Hello, I am considering using a computer as a home server. Right now, I beleive that I've got to get a bunch of NIC's, maybe RAID my hard drives, and leave the computer on 24/7 (while downloading torrents ). I have a Phenom 720, a Pentium 4 478 3.0ghz, and a Pentium 3 800mhz. I'm planning to host 2-3 low traffic websites. I have a 100mb router, and I can get a 1g switch if necessary.

-Would paying 3rd party website host be better, or using a free service such as Google? (Anyone know any other free hosts?)
-Which computer should I use for power efficiency on low traffic? (completely unheard of websites, distributing address on business cards)
-If I want a home server to host websites, can I plug it in a router/switch and use a stattic IP or do I have to plug it in a modem and use it as a Gateway? Which would be better?
-Do I have to change any hardware? What software do I need, such as Macromedia Dreamweaver?
-What's Coldfusion, and how/should I use it?
-How do I put the website up, and will my ISP (Rogers or Acanac) allow it?
-Is there anything else I should know? Again, I'm a complete newb to this... still considering hosting it myself or letting a company host it for me.
-Are there any websites to guide me through the process?
-Do I have a completely wrong idea of hosting a website from home?

Thanks for any help, I greatly appreciate it.

Yea I know I've gotta do that, but right now I'm tyring to find answers to questions that I have before 'learning as I go'.