Early 2008 Mac Pro Random wake up and other oddities

When I first purchased the machine in 2008 it ran flawlessly under Tiger I believe was the OS at the time. Ever since I upgraded to later iterations of OS X, my machine would randomly wake up from sleep but it's not a full on wake as the monitors don't turn on, just the audible click sound from the Mac and a few minutes later will go back to sleep again. Happens 3-4 times through the night when I'm sleeping.

Secondly, when I wake it from sleep, my optical drive will no longer be available. I have to do a full hard restart to gain that functionality again only to lose it again if my machine goes to sleep. One last thing is when I initiate the sleep process, it takes a good 30 seconds before it actually goes idle. Never had these issues with Tiger (could have been Leopard).

Thanks for any insights.