Answer:
1.) because they thought it was the only way to get into the afterlife
2.) because the pharaoh was thought to be a god in human form
Step-by-step explanation:
1.) The Egyptians believed that you had to go through a certain 'rite of passage' to get into the afterlife, and if you didn't preserve your body right, your body wouldn't appear all the way in the afterlife. So the long process of pyramids and mummification was deemed necessary.
2.) The Egyptian gods were believed to only be able to come to earth through a human host, the gods would pick this host and then rule as king or pharaoh of Egypt. But, with the pharaoh thought to be a god, the people of Egypt obeyed, either out of fear of being struck down by a god, or out of their desire to serve and please their deities.
hope this helps:)