You can make a eq platform for your dob which would be great for the milky way and low mag ap work. I'am currently working on cooling a 1100D and yes the cannon entry level camera's arn't great at 1600+ but the same goes for any camera in the price bracket IMO. You can build a cooler box which will give it a good aided chance and I've seen some crazy results with the 1100D at iso 3200 once cooled. Like the above poster said using dark's will help rid the noise once processed. Just google
dark frame subtraction batch this will help you buy not going through each frame by hand, prey adobe lightroom soon does this
For the milky way why not try a barn door tracker, cheap and easy to build
http://en.wikipedia.org/wiki/Barn_door_tracker a quick google with barn door tracker plans will have you going in no time.