Blazing Saddles/Headscratchers

Concerning Blazing Saddles but other films more generally, why is Mel Brooks still allowed to work in Hollywood? Consider that in Blazing Saddles, his cast ran amock and disrupted the filming of a musical in the next soundstage, in Spaceballs a cameraman was killed by Dark Helmet and in Robin Hood: Men in Tights, Mel Brooks fire arrows of fire into an innocent village just to create the title sequence.

Refuge in Audacity. Because of the way that he blatantly show these things happening in the movies instead of cutting the sequences in question, people think that it's All Part of the Show. Reputedly, he had the family of the cameraman killed when they made inquires into the accident.
Fear.
- Lord knows I wouldn't stand up to the man. My thatched roof cottage is all I have.
Corrupt Corporate Executive syndrome? Who cares who dies/gets hurt as long as they get their paycheck.
He's got the Schwartz! It's far too powerful!
Of course, that cameraman's death wasn't real. A direct hit from a real light saber would've set his clothes on fire.
- They use "safety" sabers in the movies. They are still sharp, but they don't radiate as much heat as real light saber. They can't actually deflect blaster rounds though, so those have to be composited in.
"Piss on you -- I'm workin' for Mel Brooks!": clearly, Mel Brooks is the secret power that governs Hollywood, and as such can get away with absolutely anything.
There's more than one Mel Brooks, so if you get rid of one, another just takes his place. The Commentary for Spaceballs says that the writer, named Mel Brooks, did the movie as a favor for the Producer, also named Mel Brooks, who did it as a favor for the director, also named Mel Brooks. The actor who played Skroob, also named Mel Brooks, did it as a favor as well.

What was the meaning behind the Cecil B. DeMille joke?

Waco Kid: "I must have killed more men than Cecil B. DeMille."

Since Cecil B. DeMille 'killed' so many people in his movies, his 'kill-count' must be very high. These days, someone might say, "I've killed more people than Quentin Tarantino [has killed in his movies]!"
There's an old joke: DeMille is planning an epic battle scene with tens of thousands of extras. The producer demands, "How are we going to pay all those people?" CB replies, "We won't have to. We'll use real bullets."
Cecil B. DeMille made a lot of huge-scale epic movies, often with battle scenes involving hundreds of participants at a time. Ergo, lots of people 'died' in them.
He also had an abominable safety record and often displayed little to no value for human life, I believe.

What's the significance of the Yes and No on the cow's ass? Is there a "Complete Annotated Brooks" you can pick up somewhere?

It's a joke on old school buses, which had "Yes" on the side which you could pass on. At least that's what my dad told me.
- Not just old school buses. Half the trucks I see on the road these days have Yes/No or some variation ("Pass/Fail", "Live/Die", and so on) on them -- and if you're wondering why, it's because trucks make wide right turns, and if you try to slide up past them on the right at a corner, you may find yourself plowing right into the side of the cab.
- And here, I'd been assuming, for my entire life, that it was some kind of sex joke that contemporary audiences would have gotten. Huh.

When Sheriff Bart clapped his hands together to trap the chess piece, he opened them and looked surprised that it wasn't between them. Shouldn't he have been able to feel that it wasn't between them as soon as he clapped them together? I know, Rule of Funny.

...Nope. Have you ever been so sure that there was a bug on you that you could feel it moving around? You might know there's no bug, but you think there is so strongly that you can feel it. Since it would be so improbable for the Waco Kid to succeed in having taken it (and him not having seen it) it would be no surprise that his brain would simulate the chess piece being in his hand because it couldn't comprehend any other situation. The Waco Kid's reflexes simply exist outside the bounds of what we perceive to be reality.
Maybe the Waco Kid missed the first time and actually snatched it after he opened his hands.

I have this nagging feeling everyone gets this but me, but what is the "Baby, I'm not from Havana?" line about?
- You're not the first to ask. According to an answers column on Yahoo!, it's from an old stereotype that Cubans can... go a lot of times without needing a break.
- This Troper always assumed it was a reference to something long and brown: a cigar

Sitting Bull is an Alter Kocker because...?
- Because Mel Brooks thought it would be funny.
  - And as it says on the main page, in old days, "dirty white" (Jews and other Eastern Europeans) actors were frequently cast as Native Americans who would speak in their native tongue.

Which hand does the Waco Kid shoot with? In his conversation with Bart after their chess game, he said he shot with his shaky left hand. But later we see him shooting with his right hand.
- His right hand. He used to shoot with his left until he got the D Ts.