Great response, and your first point brings up an issue I've discussed recently with friends regarding religion. When someone like myself who is not religious thinks of time, it's generally in the context of "I only have so much". However, for the people who believe in eternal life, I wonder whether time really means as much to them as it does to atheists/agnostics, since if there was a promise of eternal life, it may seem to be silly to worry about the years left in your life on Earth (completely speculating here, as I'm not very familiar with these beliefs).
I like that nugget you included, no matter how depressing some may find it. It really is on us to make the most of this game. And you're right, the promise of immortality would only sound appealing if you still have hope or reasons to get up in the morning.
The idea of reduced compassion is compelling and slightly terrifying. I would hope we would not evolve into beings who cared little about the short or long-term effects of our behaviors due to the simple fact of guaranteed survival for the other party. Alas, here will always be some who would use this power to their advantage, the human instinct will always have a primal thirst for power or conquer to some extent.
I was with you until your last point, but it's minor qubnle. I believe that human aggression is a habit, not instinct. The reason being is that humans thrive on learning akilla and making them work. Cooperation is baked into our genes - I've seen living proof of that. The success of humanity is built on cooperation and every act of aggression hinders that success.
Therefore, there is no "primal thirst" for power or advantage. The desire for advantage is learned behavior and habit, nothing more.