Yeap, the stock task manager is gone with ICS. I never had any luck with it...probably because I had an app or non-stock launcher installed that interfered with it. Smart Actions is a good alternative and will generally improve your battery life. There is also an app on Google Play called Juice Defender (free and paid version). I've used it before and found it to be more comprehensive than SmartActions (greater ability to control what runs and when). The paid version gives more options and control than the free. What ever you decide to try out don't use a 3rd party task manager/killer...they generally will use more battery than they save and will usually cause other undesired behavior.
Go through your list of your apps, any app that has a disable option can be disabled... there are even some that can be uninstalled without issue like Blockbuster, Madden12 and a couple others I think... as far as an entire list to freeze with TiBU, a quick google search should find you one..
