1. Transactions won't change noticeably since the gas costs won't change and the network won't have more capacity.

2. The 'demand' from mining for GPUs is over-rated. It was a brief problem years ago. You are correct that energy usage for validation will go down.

3. One difference between bitcoin and eth... ethash is a memory hard algo so it doesn't require the fastest GPU. 4-5 year old GPUs are more ROI efficient. Everything is bound in the speed of the memory controller.

4. To be seen.

5. 'staking' today is just depositing ETH into an ETH1 contract that doesn't have a withdraw function. It will require forks to add that functionality.

6. Correct.

7. Correct. Although this likely won't have an impact on price like people think.

8. A fork could always change things.