I thought it was kinda interesting that this is the first time you see Toph as being??"Weak" because of her blindness. She was basically helpless trying to get across the ice and she couldn't swim...

Isn't the first time she's this helpless did you forget the previous episodes:

The Library and The Desert,

when she had trouble with the sand...

mmm! sand puddin'

I thought the ice was okay, but the "I can't swim" thing was sort of strange to me.

But then, if she could swim, I'd be surprised. Her parents probably wouldn't have let her take swimming lessons.

But see, even in The Desert and Library she was on sand. She was still on earth. She could kinda see but it was all burry. On the ice- she's completely blind.

Toph's an Earthbender, unless an Earthbender lives near a large body of water, I doubt they would like to swim. Like how Appa, who flies and can Airbend, doesn't like being underground. Even if Toph could see and her parents allowed her to take swimming lessons, she probably woudn't want to swim.

Say Toph did rely on vibrations to find her way. There'd be vibes on metal vessels, and vibes on ice bridges, but distances would be distorted compared to what she's used to.

I've often wondered what the extent of Toph's earth-sense is. We know that she can't see on ice, and that sand is all fuzzy to her, but when they borded the drill, Toph didn't seem all that worried about not being able to see. Remember, she didn't want to go in there beacuse she couldn't bend, not because she couldn't see. And Toph was able to to tell it was a boat buried underneath the sand in "The Desert" when she struck her foot on it, which means that she can read vibrations off of wood...

I have an hypothesis; If it is solid and earth-based, Toph can use the vibrations to see, even if she can't manipulate the elemeant.

She says in that episode when hitting the boat:
(after katara asks; how do you know it's a boat)"Believe me I kicked it hard enough to feel plenty of vibrations."

Toph can only feel those vibration due to Earthbending...no Earth means Toph is as blind as well...she's blind already

It's very hard to explain, if you see the episode The earthbending tournament or watever it's called then it explains that toph can sense the vibrations in the earth, know when some one is gonna move and how they are gonna move. Watch the episode, u'll find out