Can the champagne color pass for gold? Or is it really more of an off-white?

Yes it can pass for gold. I purchased it to match the color scheme of Easter colors with accents of gold. It was a carousel themed party.

Is this item sheer/see through? I want to be able to wear it to a party without my underwear showing

I wore it to a work party with shorts under it. I am 5'4", the skirt came a few inches above my knees and my shorts could not be seen. There are many layers that poof out quite a bit. I wasn't worried about it being see through but was concerned that the skirt may lift up if I was running around. I think the skirt is well made and perfect for what I used it for.

This is a very hard question to answer. It’s going to depend on the size you order. Plus the edges are cut jagged like triangles. I ordered the large, it comes to right above the knee in some spots and is about 38-40” long. I love this tutu it’s thick and there are lots of layers.