Protect/hide certain folders

1.) System Preferences > Spotlight > Privacy

2.) Yes, you can use chmod on a folder to adjust its permissions so other users won't be able to access that folder/file. This won't password protect them of course. There's a number of password options depending on the level of security you need. Try out MRoogle to find threads here that have discussed this thoroughly. You'll find options like an encrypted disk image and TrueCrypt.

 

1) http://mozymac.com/forums/f6/how-disable-spotlight-30/ this video will show you how to disable spotlight for some files or folders or all of your files and folders


2) http://mozymac.com/forums/f6/how-create-encrypted-disk-image-mac-os-x-37/ this will show you how to create encrypted disk images with password protection


since your so much into security here is a link for list of security tutorials for mac os x:

http://forums.macrumors.com/showthread.php?t=744582