2. Based off canon, Palpatine gave secret orders regarding a contingency where he sent several fleets and military assets in case of his death some of which was to seed the new order within the unknown regions. So he could have ordered them there postdeath plans Or they naturally assembled.
4. Hux was the son of brendol hux one of the leaders of the contingency. After his death at the hands of phasma in a conspiracy with younger hux, hux takes over his father's position as one of the leaders of the new order.
Prior to his father's death, he is looked favorably upon by gallius rax, Palpatine's trusted admiral that personally carries out Palpatine's contingency. I think either Palpatine or rax had larger plans for him which I believe is why he is in charge. He is maybe viewed as having a big role to play in events by those in the force who can see into the future. That would be my guess.
I believe we will see a revisit to jakku as Palpatine was very interested at a particular dig site, which is where he met gallius rax as a little boy. Rax would later make child soldiers out of those from jakku, and the orphanage from which he came that wads nearby the dig site. Some of these child soldiers were shaped into vicious killers by hux's father, but was transferred to younger hux by orders of rax. So although I kinda repeat the story, it should be noted that rax, the person most apprised of Palpatine's plans, placed younger hux in his position along with many other child fighters that would form the base of the new orders military might. Please note, those child fighters came from jakku.