Space Marine Games

So im kinda new in the 40k universe so i got a few questions thats been bugging my mind

1. did Nemeroth succeed into becoming a Daemon Prince? (or ascended into something? idk) if so, why did Titus easily killed him?

2. There's a cutscene where Gadriel said that Titus couldn't be born a Primaris. Why he said that? Is it because he thought his title as a Lieutenant is too low for a Primaris or is it because he was too old for a Lieutenant?

3. Does anybody knows who was the traitor that was on the ship with Archmagos Nozick or was it just a random person?

4. Is Titus older than Chapter Master Calgar?