Taskbar Problems

I have the notifications section set to tell me when I receive mail. At
first it did now it doesn't. Looking inside I find that it is now in the
section of things the were in notification and arn't any more and I can't
move it. Anyone know how?

The other problem is at the other end of the taskbar which appears limited
to showing three items with rest hidden but I have four that I use every day.
Any way of changing it?