Dell does provide the repair guides on their website for battery replacement. As far as the GPU, you're sol. It's soldered to the board as far as I know. And they don't sell just the graphics chip to consumers since they're manufactured for the specific use of mobile graphics? And for your cooling pad, I wouldn't know. Personal preference I suppose
No. The 7700HQ is a mobile processor, and it also uses BGA (ball grid array) instead of Lga (land grid array). Meaning, it's soldered onto the board. It also uses a different socket than the current Intel processors.