HTC Desire :: Air - Speed Velocity Of An Unladen Swallow?

After reading on here that task killers were a MUST have I was running advanced task killer. However my phone has been lagging recently and after reading a bit more people were suggesting Task Killers were the cause of this, I uninstalled Advanced Task Killer and installed Android System Info. Since unistalling the Task Killer the phone is much faster in general, by my perception. Using Android System Info I can see that available memory is at times about the same as after performing a kill, suggesting that Android handles resources well left to itself by auto killing apps or processes when ram is low. It shows info on when the system considers ram low and starts killing apps as well as loads of other system info and logs. Looking at the Tasks tab shows how many apps are running and the memory used, but crucially also shows the CPU usage of thoe apps. Generally the Apps in memory are using ZERO cpu usage, My quadrant benchmark with Appkiller was 538, without it is 567. Not massive, but still BETTER. I would like anyone to comment on the following:-
1. Does Killing and restarting apps decrease battery life due to increased CPU Usage ?
2 Does memory itself use Battery life if the items in memory are not using CPU ?
3 Does having low available ram matter when the CPU actually does the work and can Android kill fast enough when Ram is required to meet an applications requirements?
4 What is the air-speed velocity of an unladen swallow?