Mouse scrolling is, I believe, controlled from your /etc/X11/XF86Config-4 file. If you open that in a text editor like vi, emacs, jed, etc. (as root), look for a section like this:
... (other stuff)
Add this line to that section:
Option "ZAxisMapping" "4 5"
If it's already there, it may be that the wrong mouse protocol is being used. I believe the line which says "Protocol" should read "IMPS/2".
As for your fan... I don't think my fan (CPU, case, or power supply) has ever run at anything other than 100% for years, and it's still OK, so you probably don't have to worry about it too much. You may want to check out the Linux kernel's various power management features (ACPI and APM) and related software, though, which may be able to control fan speed. Not sure, since I haven't used them.