Answer to Question 1
Pluto is predominantly composed of ice and rock, unlike the terrestrial planets which have little ice and the jovian planets which have (proportionally) little rock. Further, its orbit has a much higher eccentricity and inclination than the terrestrial and jovian planets which orbit close to the ecliptic plane. Finally, there are many objects known, most smaller but at least one larger, than Pluto with similar compositions and similar orbits whereas the other planets have no other comparable companions in similar orbits.
Answer to Question 2
Low-mass stars swell up as red giants, stabilize with the helium flash, then again evolve into supergiants, shedding planetary nebula and leaving the white dwarf core exposed. By contrast, massive stars may form supergiants and continue fusing heavier and heavier elements up to iron, then end in much more violent deaths as Type II supernovae.
Three ways that factors affect mortality in response to changes in population density.
History of the number of observed sunspots during the last 250 years, which shows the ~11-year solar
Effects of Earth’s Changing Orientation: Solar Angle
What Happens to Incoming Solar Radiation?
Average Distribution of Incoming Solar Radiation
Solar System