No
No
Yes
Yes
Yes
Yes
Yes
The plural of buyer is buyers. As in "the buyers have arrived".
No buyers remorse law in any state applies to the purchase of an automobile.
No.
Buyers are consumers -- the people in an economy who purchase goods and services. There are also professional buyers, who work for companies to get the best products at the best prices.
You can usually purchase buyers products protection at the store where you are making your initial product purchase. This is generally available whenever you are buying electronics.
When buyers will purchase exactly as much as sellers are willing to sell, Equilibrium has been reached.