I don't know much about Xbox 360 except mine keeps going to the repair shop. What I was wondering is does the Elite hard drive thing fit all types of 360 and in the case of getting a whole new 360 can I re-download the DLC again without paying again ? I have a feeling I may get a new one but don't know anything about getting the DLC I bought onto a new box.

Depends on the model. It won't fit on a new slimline xbox, for example. But you can get a headswap cable to copy your profiles and save data.

All DLC can be downloaded again, free of charge. It's tied to your Xbox Live Profile not the kit. So unless you create a new live profile you should be fine.