I've seen it noted by better critics than me that when people criticize movies by fixating on hyper-specific inaccuracies or contradictions (the Cinema Sins method) they're usually expressing the fact that there were deeper underlying flaws in the movie itself that meant it failed to give them a reason to overlook those hyper-specific complaints.

After all, if the things you've listed here were reason enough to hate a film, on their own, you're basically just saying that you shouldn't watch movies. If you know enough about where and when a movie is set, you're guaranteed to be able to find those kinds of inaccuracies in any movie you watch, with very few exceptions.

The real problem here, I suspect, is that Kingdom of Heaven, as released is a bad movie. The director's cut, on the other hand, is incredible. Ridley envisioned this as a sprawling Lawrence of Arabia style historical epic, and that's the film he made. That film was then butchered to fit what the studio thought would make a good theatrical release.

The director's cut will not, to the best of my recollection, solve any of your specific complaints, but it is a far, far better movie.

Of course, it is possible that the version you saw was the director's cut, in which case I'm very sorry, movies set in any version of the real world just might not be for you. Or you're just not really a fan of historical epics or something. I dunno, you do you.