Overall, the Gintama anime is a decent adaptation of the manga. There are some minor differences for better animation or pacing, but the core story and characters remain the same.
The Gintama anime is considered a pretty faithful adaptation of the manga. It keeps the essence and storyline intact. Though there are occasional variations to make it more engaging on screen, they don't stray far from the original.
It follows quite closely. The Gintama anime mostly adheres to the manga plot, with only a few tweaks here and there that don't significantly change the core story.
There were many animes that were better than Silver Spirit. The specific recommendation of an anime depended on one's personal preference. If you like comics, adventures, and comics, then Attack of the Giants might be more suitable. If you like relaxing, warm, and fantasy anime, then the Gate of the Fate Stone might be more suitable. If you like mystery, suspense, and psychological anime, then Detective Conan might be more suitable. If you like historical, cultural, and artistic anime, then Black Deacon might be more suitable. Everyone had different preferences, so it was up to them whether a recommended anime could satisfy their needs.
Not all of them. While a significant portion of the Gintama manga has been adapted into anime, there might still be some storylines or arcs that haven't made it to the screen yet.