Hi.
Suicide NPCs is a known issue, still working on a proper fix for this.
You can buy new NPC crew from slavers(the ones that are not hostile) or from some trading stations(they might have a guy there who has engineers for hire)
When you loose the Falcon ship - it's GG.
You can restart the play-through from the in-game menu - Press escape and select Reset server(you will need to reconnect)