Rotation will cause spectral lines to smear, because part of the galaxy is rotating toward you, and part is rotating away. So the parts that are moving toward you will be blueshifted in relation to the center, and the parts that are moving away will be redshifted in relation to the center...
these are 'rough' estimates, and there is some variation in opinion as to where exactly these boundaries should lie. The final events in a star depend on more than just mass, although its mass is the single most important factor.
Stars with masses of 0.4 though about 8 solar masses will end...
You've pretty much got it. I would add
1a) The proposed existence of Nibiru makes certain predictions including a regular disruption in the orbits of the planets, including earth, which should show up in the geological record. No such cycle is observed.
1b) If Nibiru existed, and had made a...