changes to size and density of the sun?

Answer 1

As it reaches the end of its life on the main sequence, (its last few billion years) the Sun will become gradually larger, more luminous, and less dense. When hydrogen fusion in the core stops, it will become much larger and less dense. It's outer surface will be much cooler, even though the total energy output (luminosity) will be much higher. This is called the red giant phase.

Answer 2

1: 5,000,000,000 years later estimated
2: The sun will run out of fuel
3: It will increase to Red Giant
4: It will shrink to white dwarf star
5: after thet it will become black hole and clean up the galaxy.