Heating Control Solution- Help Needed!

Okay so I've done some reading and am growing ever more enthusiastic about this project. I have a million questions but I'll stick to just a couple for now:

Starting from the very beginning - What Arduino board would I be best using for this?

Regarding the nuElectronics Datalog + I/O shield - which I think would serve me well after reading up on the use of DS18B20s with it- is it possible to both read AND write off of the SD card with this shield?

Or do you feel there is a better fit for my needs than that shield?

Thanks!