It's not enough to believe in God. Satan believes in God.
It's necessary to repent of your sins. To accept what Jesus did on the cross as payment for those sins. To accept Jesus as your Lord.
No, all your expectations won't be granted. I expected my first wife to be healthy and live. She got sick and died when she was 30. I expected her two pregnancies to result in the births of two healthy children but instead both children were stillborn.
The Bible speaks of trials and tribulations.
(James 1:2-3 NIV) Consider it pure joy, my brothers, whenever you face trials of many kinds, {3} because you know that the testing of your faith develops perseverance.
(1 Peter 1:6-7 NIV) In this you greatly rejoice, though now for a little while you may have had to suffer grief in all kinds of trials. {7} These have come so that your faith--of greater worth than gold, which perishes even though refined by fire--may be proved genuine and may result in praise, glory and honor when Jesus Christ is revealed.
Are lives won't be easier when we become Christians. They typically become harder because God wants us to become spiritually mature.