I'm in the beginning stages of writing a comic that is heavily inspired by Star Wars. I don't have any plans for a magical power wielded by knights like the force, but the universe I'm imagining is quite similar. It involves a technologically advanced society with integrated aliens and many colonized and civilized planets. Some of them being one huge city like Coruscant or Taris. (Sorry if I'm spelling anything incorrectly.) The actual story will be centered around a group of mercenaries, but is the universe I have in mind too much like Star Wars to be unique?
In a word, no. The proposed story you intend to write sounds like it has an initial setting similar to many, many Science Fiction stories I have read, but there's nothing about your description that especially screams out Star Wars. Star Wars simply makes use of some basic setting features that are common to many Sci-Fi stories. Many. And that's fine. These things are just commonly used features and tropes.
As this is a comic, the visual aspects will probably be the biggest giveaway as to whether you're edging too closely to Star Wars. Should be fine.
This could easily be the empire in Azimov's foundation (minus the aliens part), which predates Star Wars by a good bit; in those broad strokes you're good. More specific things could be too star-warsy depending on what they are. Don't be afraid to write a space western, it's a cool genre.
Based on Japanese films which were based off westerns, which were based off gaucho literature of Argentina/Uruguay, which were based off of Spanish picaresque, which were inspired by Don Quixote, which was a satire of Chivalric Tales, which were also based off of something else, ad eternum.
Precisely. Everything is copied. Nothing is original. Unless you're writing about Luke Skywalker and the Force, you're not copying Star Wars.