Main sequence stars are found in all galaxies.
The HR diagram does not reference stars on their way to the main sequence, only during or after.
Stars are classified by the H-R scale. They are classified by their luminosity and their temperature. They can also be classified by stage; our sun is a main sequence star while the center of the milky way is a black hole(the corpse of a super massive star).
A rough guess puts the number at 1 in 13 of all stars on the main sequence are type G stars - similar class to our Sun.So around 7.5 billion to 30 billion.
Yes, there are young stars in the Milky Way Galaxy.
The Milky Way is a huge group of stars, somewhere between 200 and 400 billion stars. The stars themselves, or the Milky Way in its entirety, is not in line with anything.
There are about 33% F type stars in our Milky Way.
All stars that are in hydrostatic equilibrium are on the main sequence, where outward thermal pressure from the hot core is balanced by the inward gravitational pressure from the overlying layers.See related questions
the milky way is a galaxy, there are billions of stars in the milky way galaxy
The Earth is in the Milky Way Galaxy. We can see stars at night, so yes.
The milky way is not a constellation
The Milky Way is our galaxy.
Sun, moons, planets, asteroids, meteors, and STARS! (Our galaxy MILKY WAY)