1. Well, If everything is working fine, then I wouldnt worry about that. I only worry about it when everything is NOT running fine :P
2. None that I know of. But you need to keep your hard drive as de-fragged as possible... As usual.
3. Synaptic Package Manager. It downloads the applications directly from Ubuntu's servers. It's somwhere under the tool's menu. I cant remember what these menu's are called off hand, but you can access it from either the "Tools" menu (if that's what it's called), or a similar application that downloads the programs from the same servers, from the Bottom of the menu that is to the far left of the top corner of your screen
If you know what program you want, you can open up terminal, and do:
sudo apt-get install <programname>
For example, If I wanted to download... Say, An FTP Server, i would do:
sudo apt-get install vsftpd
This would sort out any other programs/services needed (called Dependancys) to run vsftpd (Very Secure FTP Demon), and then download & install it.
4. Have a look on: https://help.ubuntu.com/community/Webcam
- A number of cam's are supported.
Sorry if this doesnt make sense... I will re-read it in a minute!
Good luck, and if you need any more help, just yell... Or even better, Ask on our IRC server (Link in sig)