I'm no expert, but I'd say the 1100D is pretty well matched to an 8" newt, should get you good resolution.
If you decide you want extra sensitivity down the red end, you can always get it modded. And for cooling, you can make a cooler box for use in summer relatively inexpensively. Take a look at the thread in the DIY/ATM section. I've found the noise to be quite reasonable as you get into single digit temperatures...pros with their big cooled CCDs would undoubtedly disagree
