Computer hardware questions. Couldn't find newsgroup on microsoft

Hi, I have a few questions about hardware and what it is. I looked he

http://www.microsoft.com/en/us/sitemap.aspx

But there was no newsgroup. I use XP, so I need hardware. That's the only
way I can tie these questions into using this board. Anyways:

- What is an IEEE 1394 port (I think I have the number right). It seems
related to something about audio or video?
- What's a VGA port?
- What's a RJ-45 Ethernet connector?
- What is a serial port? What goes in it?
- What is an eSATA drive? Is it a newer SATA hard-drive? Is it better or
what's the difference?
- Why does RAM have to be in pairs (eg: 2-1Gb, or 2-512Mb, 2-2Gb)? I kind of
understand it interacts well or something, but why can't I use only one 2Gb
or 4Gb? Why can't I use a 1Gb and 2Gb combination or a 512Mb and 4gB (I think
I saw a 4gb in a store)? Can it be done, do you have to set some options up
for a non-same pair to work? Will it work?
- How can I tell when I need a new or larger power supply? If they are
overused do they burn out or crash and erase your system? I know there are
features to monitor my system, but how can I tell I have to upgrade a 300
Watt to a 500 Watt for instance?
- Can someone change their Processors? From what I'v seen, people seem to
sodder them on, or theya re already attached to the motherboard, but I think
this can be added to or changed. No?
- For what situations would someone recommend adding more that one fan in
your computer? How many hours of daily log-time or what situations make 2+
fans worth it?

Thank you.

Brian