Raven knows the game very well.. A side note to number 2...

As long as you own a home world you can't be eliminated.. What this means is.. If you find a weak home world it would serve you well to acquire it. If you take someones home world and it is the "only" home world they had, they will be eliminated from the game. If you own more than one home world, you will be safe. So if you had taken over 10 home worlds, someone would have to eliminate all 10 of your home worlds to eliminate you from the game.

Just because you wipe out someones home world, doesn't mean they are gone from the game.. That might have just been one of their side home worlds, and now you have poked the nest..

For #3 we like to compare the game to a game of survivor. Diplomacy is what ever works at the time... This isn't your kiddy game where you are protected. You can be eliminated, and if you are it's time to learn and move on to the next game. Remember the names you encounter, that's the name that player will always have. Revenge is a dish best served cold (in the immortal words of Khan).

While there isn't going to be just a single player left when the game ends, there could be a lot of players left when the win conditions are met, all the players will get points depending on their ranking, and what they achieved in a specific game, even those that are eliminated will get something. Just play to have fun, and enjoy the game and strategies that you create. Each game starts a new, so you can take what you learn in one, and apply it to a new game.