These two decisions shape a lot of how Episode 3 ended. Regardless of those choices, Hala and her Kree warriors storm into the chamber where Peter decides what to do with the Eternity Forge. If you destroyed it, Hala becomes immensely pissed, but it seems the fractured artifact still bestows some power to her. If you powered it up, then the Eternity Forge ends up in Hala's hands complete and fully restored. Your decisions regarding Nebula put the cyborg assassin either on the side of the Guardians or accompanying Hala in the fight, but each have their own consequences, and at least one possible outcome leaves Nebula severely injured.
Unfortunately, Who Needs You doesn't do much to advance the overall plot, at least with regards to the Guardians facing off against Hala and whatever power she has over the Forge. Instead, the aftermath of the fight leaves all of the Guardians falling down a massive cavern into the depths of the planet that housed the temple and it isn't until the final scenes of this episode that the Guardians emerge from the place and have to figure out what to do about Hala. That's not to say nothing of significance happens in Episode 4, it just feels like the developers realized they had a lot more to do and the overall plot was drawing to a close faster than they had intended.