1-Because it is not a throne of judgment for us, but a throne where grace is dispensed freely. "Grace" is charis, "practical application of goodwill, (a sign of) favor, gracious deed/gift, benefaction, divine favor."13
2-so that we may receive mercy and find grace to help us in our time of need
3-When you're in trouble, don't hesitate. When you come to Jesus' throne in prayer you'll find a sympathetic ear, divine pardon for your sins, and timely aid whatever your trouble may be. Why wait? The High Priest who is King is calling you to approach his generous throne so he can give you his rest.