Why are the options for suspend/hibernate not there or I can not select them?

There are many possible reasons, for example your kernel could be compiled without suspend/hibernate options. It could also be that you don't have the right permissions to use them.

I have put my computer into suspend or hibernate mode, but the computer is not waking up.

This was the subject of many bug reports. Please note that the power manager has nothing to do with these problems, since the kernel is responsible for these tasks. The kernel team is putting a lot of efforts into fixing these kind of problems, however, if you still have problems please report a bug to your distributor and hopefully they can contact the kernel team and possibly provide a work-around.