It seems that right after they can get the enemies neutralized so they can leave safely in local space
I don't think they care about finishing the other factions off. They just want to consume as many planets as possible to ensure they have the resources to keep up their migration, then they're off to the next galaxy. They'd probably be glad if some of the others stayed to slow down whatever is chasing them.
they seem to want to rebuild there empire right now.
This seems partly true. Based on the restore armor and shared shield techs, they seem to be wanting to restore themselves to the Vasari's former fighting strength. But from the cinematic it doesn't seem like they want to make a stand. They still want to run, they just think they have the best chance if they stop fighting immediately and take the other factions with them.
They seem to be Rogues and Pirates (Yes, even with the new up-dates I find it more economical to buy the Pirate Mercenaries rather then pay the money and resources for the equivalent with the exception of capital and some special ships)
Rogues who really want to kill all the aliens. They'll work with pirates, but I don't think its fair to classify them as such as money isn't their primary motivation. And I will gladly reduce your pirate hordes to space junks with normal TEC ships any day.
These I still say are Terrorists nation of the Sins of the Solar Empire World
I feel we had this discussion before, and I vehemently disagree. I think they were inspired by the protestant reformation and the dozens of other religious and social reform movements. Granted to the old order sometimes these groups are terrorists, but that's usually a small few after the fact.
The only Rebel unique ability that directly benefits you to suicide your ships is strength of the fallen and purification, both of which are used to buff a friendly target instead of hurt an enemy, so that's why I think terrorists are a bad comparison. Lore wise they themselves few it as a sacrifice to their own strength, and due to their control over life and death it isn't as big of a deal to them.