You can control your scheduled tasks using schtasks
console command. So you may create a task performing on system start-up disabling you tasks with something like that in .bat file:
schtasks /Change /DISABLE /TN "Start uTorrent"
schtasks /Change /DISABLE /TN "System shutdown"
And then you may create a shortcut to another .bat file enabling tasks once clicked, like:
schtasks /Change /ENABLE /TN "Start uTorrent"
schtasks /Change /ENABLE /TN "System shutdown"
PS. And it should wake up your computer from sleep if you specified to do so in scheduled tasks, but it could be put to sleep again after some user-inactivity timeout.