Stellaris: help create high Empire (2.2 + dls) (Dead Island)

I'm sure many people know about this method of games like high Empire (of civilization). Want to create and play this in the stellaris. Outline - emphasis in technology and unity, as well as a small number of planets. I want to ask for help from those who have already tried to play this Empire. The main issues are whether to take the greenhouse and pacifism or not?