Short answers, pulled from the story.
Phil Tippett created the physical form of Jabba the Hutt for Return of the Jedi in 1983. This rotund, slug-like creature appeared on screen as a grotesque crime lord who kept Han Solo imprisoned as a trophy.
Nal Hutta serves as the capital planet known as Glorious Jewel within the native tongue of the species. Its primary moon Nar Shaddaa acts as a bustling hub for trade and illicit activities throughout the sector.
A deleted scene from A New Hope was modified and re-inserted into the Special Edition release in 1997 to show Jabba earlier than originally planned. This change allowed audiences to see the character before The Phantom Menace released in 1999.
Adult Hutts resemble shell-less gastropods in their movement and general appearance within the galaxy. According to the novelization of Return of the Jedi, these creatures were born bipedal before their rump legs fused together over time due to lack of movement.
The Si'Klaata Cluster forms part of Hutt Space located between the Mid Rim and Outer Rim Territories. This special autonomous region sits to the galactic east of the Core Worlds and encompasses approximately one thousand inhabited worlds.