Good Riddles

Question: 500 is at my end and my start, yet 5 is at my heart.
The first letter and the first number make me complete.
My name is that of a king.

What am I?

Question: A swan is in the center of a circular lake but he cannot take flight from the water, only on land. On the parameter of the lake there is a hunting dog that desperately wants the swan but cannot swim. So the swan must make it to the land before taking off and must do so before the dog makes it to him. The dog is almost 4 times faster than the swan and always runs to the point around the lake closest to the swan.

How can the swan get out of the lake and take flight before the dog gets him?

Question: You struggle to regain me.
When I'm lost, you struggle to obtain me.
I pass no matter your will,
but I'm your slave to kill.
What am I?

Question: A man walks all the way around the world without getting wet.

How does he do this?

Question: A man and his boss have the same parents, but are not siblings. How is this possible?