Question: When Dark Helmet says that there are two sides to every Schwartz, is this an obscure reference to something else, besides the obvious light side and dark side of the force?
Answer: "There are two sides to every sword" is a common saying.
Question: How did Lone Starr learn to talk if the monks he was raised with took a vow of silence?
Answer: That's the joke.
Question: Planet Spaceballs intends to steal all the air on Planet Druidia. Spaceball city and Planet Druidia are neighbors. When Megamaid explodes, her head lands on a beach on a planet that presumably has air. Why not steal the air on the planet inhabitated by apes? There's apparently no air shield. Additionally, the desert planet where Yogurt lives also has air and no air shield. Two other planets, in addition to Planet Druidia, that have breathable air.
Answer: It also might stand to reason that the very fact that Druidia has a shield is what makes it viable. It almost creates a docking port for Mega Maid who was presumably designed for that very purpose. After all, what other purpose could a space maid with a vacuum possibly have?
Answer: The Spaceballs are a race of bullies, they only pick on planets they know have no defense, like Druidia. Yogart, like Yoda, was a very powerful being with mystic powers, While the planet of the Apes were highly intelligent and were most likely able to out smart a race of idiots.
Answer: In the context of the movie, the Spaceballs seem to hate Planet Druidia. So why not steal air from the planet they hate? In a more meta behind-the-scenes context... it's just better for the plot for them to target Druidia since it makes more sense dramatically and creates stakes for the story.
Answer: Its a reference to how the stars streak around the ships in "Star Wars". "Ludicrous speed" had to have a ludicrous color. It is also referencing 2001: A Space Odyssey, where this "tartan" effect occurs when Dave is in the pod towards the end of the film.
Grumpy Scot
Those answers are quite correct and possible, but how about this: Warp and weft are the two directions of yarn in weaving (of plaids and other things). It might be a very meta joke since plaid is at much higher level than warp. On the other hand, it's Mel Brooks. On the gripping hand, he was born in Brooklyn in the mid 20's and might have been exposed to the basics and vocabulary of the tailor at a young age.
Btw, it's also a clear reference to the sentence from Star Trek "They've gone to warp."