Palpitine wasn't necessairly from Naboo i think he represented about 80 planets but Naboo was  the principal in the movies so it's always mentioned. As for the EU questions. Yes Palps did have a kid named Triclossus (i think) The kid was to become the next emperor but ended up having three eyes so he got booted in favor of anakin. Our Dear Emperor was also sleeping with the Head of Imperial Intelligence, Yssane Isard. Iceheart (as she is fondly called) was given a super star destroyer that was buried under the city at corecant. Later the emperor cloned himself and Luke became his apprentice. Leia had anakin and like kill the emperor about 50 times. The only thing i can tell about the Emperors past is..... he's a powerplayer who got hungry and decided to take over. 
  
By the way about the sith apprentice killing the master, this is how it's always been, it's generally accepted that the stronger will slaughter the weaker, most lords accept that their apprentice got stronger than them and will loose the fight so that the sith can become stronger. 
  
Cough now that my dicertation on the EU is done i can go to bed.