Maybe she can't read English and signed the contract without reading it because she wanted to be a human that bad. She probably did one of those "I Agree to the Terms and Conditions" thing where she didn't (and most likely couldn't) read all 500 pages provided.
do we ever see her writing her name on the contract? It could be possible she just trusted the witch, and just scribbled something. If she give the permission, it's still legal. That's even how america works.
We're not debating the legality; of course it's legal. Ariel was an idiot and didn't read the fine print. The point is that she *can* read, and we do actually see her write 'Ariel' in the movie, in some very fancy handwriting. We get a close-up shot and everything.
No, it wouldn't. The contract was simply to get him to kiss her in order for her to become human. There was nothing in there that said she couldn't talk to him. Ursula took her voice as payment for the contract just to make it harder, but she never said talking to him was against the rules.
No, that doesn't work because she signed he name.