More than likely it was just intended it to be one big planetary shield, and it just wasn’t shown correctly with the rebel hologram. You could still have a shield gate for access to Endor.
I doubt that.
The Rebels on Hoth used their shield to repel bombardment and complicate a land assault but it only covered a small section of the planet. It was a make-shift affair and the Empire had more resources but the shield was designed to protect the station and the generator base itself I doubt it would be feasible for them to extend the shield around the whole planet as well. The construction site is huge as it is. Extending many miles into the atmosphere and surrounding a station the size of a moon.