How did Sarousch know which of the bells was La Fidele? Madellaine refused to tell him initially when he asked her, and he left her in the tent with the threat of harming Quasi if she didn't keep him away from Notre Dame. And it couldn't have been because of how bejeweled the bell's interior was, because he didn't know about that when he first saw it.
Probably when he finally had the chance to sneak into Notre Dame, he was able to look inside and realize that the bejeweled interior only belonged to La Fidele.
I think you misunderstood the question, or maybe haven't seen the sequel. Sarouch asks Madellaine which of the bells is La Fidele, before ever going into the cathedral. She leaves to distract Quasimodo without telling him. Yet when he gets to the cathedral, he's able to pinpoint the right bell without even looking at the inside of it. (He's specifically disappointed by its lackluster appearance until he realizes its true beauty is on the inside.)
She probably did tell him off-screen.
Why is Esmeralda wearing shoes? She was barefoot in the first movie, with the only thing she wore on her legs being a single anklet, but at the end of the film, she loses the anklet after wearing the white dress! And about the white dress, by the end of the first film, it would probably be the only outfit Esme will be wearing since her iconic dress was implied to have been destroyed by Frollo.
Maybe she bought some shoes? City streets are disgusting, and walking around barefoot there is just begging to get coarse, leathery feet covered in cuts and infections. It's pretty possible she was only shoeless because she was impoverished. She married Phoebus, who is implied to have money, and was no longer poor, so he presumably bought her shoes.
The crew themselves said her shoes are a status symbol.
And her old dress back? Again, Frollo presumably destroyed it and all but one of her other dresses so that he can have her executed properly, hence the white dress.
Perhaps she made a new one? Given how it's her main outfit in the first movie, it's probable that if she did remake it her memory is good enough that she can make a dress that's at least almost identical to one she wore frequently.
She probably made her first movie dress to begin with. Esmerelda doesn't seem to have much money in the first movie so it's not surprising that she had to sew together own clothes. So it would be really easy for her to just make the dress again if she made it the first time.
That white 'dress' is not actually a dress. It's an underdress or chemise, basically her underwear.
Wouldn't having gems on the inside of a bell make the tone come out warped? To say nothing of the fact that bells are specifically designed to withstand long term wear and damage from the powerful ringing whereas jewels are fragile and probably wouldn't even stand up to a week of such attrition. Also, wouldn't the Anvilicious moral of "True Beauty Is on the Inside" have worked just as well with the sounds the bells make? The decorations were hardly even needed. Let's not forget that the clapper (the pendulum-like component that produces the sounds of a bell) would probably smash the jewels into pieces.
Sarousch makes balls disappear and reappear in Zephyr's hands right before his eyes, something no amount of stage magic could do. He later makes La Fidel disappear despite it being in a bell tower in a city he has never been to before. The trick is supposed to be sending the bell down a tunnel, but there is no way he could have a tunnel connected all the way up there, especially when he didn't even initally know the bell's exact location.
