I've been trying for days to find the answer to these questions but my search-fu just hasn't been up to the task so I turn to the community for help.

The background:
I'm a relatively new Ubuntu user and I've nstalled 12.04 (64bit) on an ex-Vista desktop PC as a general purpose home computer. The machine is currently being used randomly by the kids for the odd bit of emailing/web browsing and occasionally to watch a movie/show on it.
I came across this lifehacker article to turn an Ubuntu box into a media streaming machine and I was very very interested (the computer mostly sits there so having a media centre device really appeals).
However, the box has a fairly loud PSU fan (an issue at night since it's right next to all the bedrooms) and the thought of leaving it on continuously bothers me from an energy use point of view.
I set it up to go into suspend mode when not in use. I would then WOL (using my tablet in this case) to start up when I wanted to stream something but unfortunately it seems to suspend while streaming. Which is annoying when it happens while watching a show.

QUESTIONS: Can the suspend mode be modified beyond what's available on power manager?
1) Specifically is there any way to suspend as well as wake up remotely (this would be ideal - that way when not in the vicinity of the box I can wake it up when I need it and put it to sleep when I'm done w/out having to worry about timers).
2) If not possible, is there some means to use a longer period than the default "1hr" of the power manager? For example have it stay active for 3 hours before autosleep mode? THat way I can at least know it won't conk out midmovie.

Thanks!