Usopp returning from? If you mean the timeskip, it's around episode 517.
332 and 333
Episode 236
it is in episode 3.
Yes. Sogeking is a masked disguise that Usopp used, so he could support the Strawhat pirates even though he had left them. Only Luffy was fooled though of course.
He is Usopp. He used the mask and the name because that time he and Luffy had a conflict.
I'm presuming your refering to the fight between Luffy and Usopp back on Franky's island WaterSeven/Aqua Lagoona. Well they were fighting over whether they should leave their ship, Merry, behind as it had become broken beyond repair after their visit to the Sky Island. Usopp wants to save and repair the Merry, but Luffy see's sense and knows it's safer to leave the Merry behind. Usopp challenges Luffy to a dwell, which Zoro forsees and prevents the others from getting involved and stopping them. Luffy, enevitably, wins.
If I can remember correctly, the Strawhats gathered on the edge of the bridge at Judiciary Island and confronted the CP9, Robin and Franky, who faced them on the small floating island above the giant waterfall. Usopp, disguised as Soge King, presented everybody with his new weapon, Kabuto, when Luffy asked him to burn down the Marines flag. From what i can remember, i don't think there was an episode explaining how Usopp got his new weapon.. Anyways it's on either episodes: 278 or 274 =]
Ussop loves Nami. It is obvious because when the crew is always gone they are always together. It is true because he is nice to her as well. There you go.
As of the latest manga, Roronoa Zoro - Swordsman, Usopp - Sniper, Sanji - Chef, Nami - Navigator, Tony Tony Chopper - Doctor, Frankie - Shipwright, Nico Robin - Archaeologist, Brook - Musician.
If you are refering to the One Piece anime character, he is the sniper and fourth member to join the strawhat pirates, ~he also paints flags and shoots cannon balls well. that's all he does (:
The main pirates are the strawhat pirates which consist of 9 members Captian:Monkey D Luffy Crew:Zoro, Sanji, Nami, Usopp, Chopper, Robin, Franky, Brook.