“But if there is a train to the Emerald City, why did Galinda make poor Dorothy walk all that way?”
She probably didn’t. The Wizard probably destroyed the train himself to make room for his wonderful road, yet another way he claims to do wonderful things for Oz all while moving them backwards.
“But couldn’t Galinda use her bubble to transport Dorothy?”
Probably, but I’m guessing Galinda knew the Wizard wouldn’t be so kind and receptive to someone else from our world coming here, because Dorothy could actually recognize him as a fraud and call him out on his bs. Dorothy, like Elphaba, is a threat to the Wizard’s power and the fact that she murdered the sister of his political enemy on arrival isn’t helping her seem less threatening, so Galinda is stalling while she figures out how to protect this poor girl and maintain appearances. Hence the whole “making her walk in heels” thing plus it provides a cover story for why Elphaba “can’t” kill her to reassure Dorothy that she’s safe from the Wicked witch: she still wants her dead sister’s shoes.
Also, Elphaba probably knew the Wizard would try to manipulate/hurt Dorothy and the others too. Even if she didn’t know who Fiyero was, she’d still be worried about Toto and the lion given what the Wizard does to Animals, which is probably why she uses the poppies to put them to sleep. The only people not enchanted are Boq and Fiyero. In the Wizard of Oz, it’s because they’re not living and Dorothy, Toto, and the Lion are, but in this case, it might be because Elphaba recognizes them.
“But then why would Galinda use her snow to wake them up from Elphaba’s poppies if Elphaba was trying to protect them?”
She probably didn’t. Morrible is the one who controls the weather. And we know that Morrible has no problem using her talents to make her current/former students look better or worse.
