Honestly I would recommend the Toshiba Portege z20t. It is a great 2 in 1 at an affordable price. It has amazing battery life, up to 14 hours.

If you didn't replace the thermal paste, a new cooler will be useless. You need to replace the thermal paste as well. Go to your local computer store and ask for 95 watt tdp thermal paste.

The gears should not require lubricant. If you need to, contact the Sphero staff and they will tell you what to do.

It is definitely possible but will take multiple hours and may not work. I would recommend taking it to an authorized repair provider or to apple directly. If it is still under warranty apple will repair it for free. Do not try to bend the case yourself. It will just cause more damage. Also if it is under warranty do not try anything at all. Just go to apple.

From what you have said, it is probably not possible to repair this kind of damage. If you don't mind paying apple will probably repair it. My recommendation is buying a new apple watch.

Unfortunately you will need replacement earpods. They are cheap and can be picked up at apple for under $50 (AUD)

You will at least need a new logic board. What else you need I don't know. If this is your phone replace the parts you think are necessary, if it's someone else's phone replace everything.