Glacial Chasm Timing

[Lunk]

If I have a [card]Horn of Greed[/card] in play and play a [card]Glacial Chasm[/card], do I get to draw before or after choosing which land to sacrifice to the Chasm?

If I play the Chasm, but can't sacrifice a land to it, do I still get to draw a card for Horn?

If I have a Chasm in hand and a [card]Fastbond[/card] in play (and have already used my 1 "normal" land drop), when I play the Chasm will I take 1 damage from the Fastbond, or will the Chasm prevent that damage?

Finally, can a player "respond" to the playing of a Chasm?  I know a land normally can't be responded to, and I assume the same holds true for the Chasm, but I wanted to make sure that the replacement effect didn't open up an opportunity.

Thanks!

[Jebus]

If I have a Horn of Greed in play and play a Glacial Chasm, do I get to draw before or after choosing which land to sacrifice to the Chasm?

You'll have to perform the sacrifice before you can draw.

If I play the Chasm, but can't sacrifice a land to it, do I still get to draw a card for Horn?

Yes, you still draw.  Note that you must sacrifice a land if you have one to sacrifice.

If I have a Chasm in hand and a Fastbond in play (and have already used my 1 "normal" land drop), when I play the Chasm will I take 1 damage from the Fastbond, or will the Chasm prevent that damage?

The damage is prevented.

Finally, can a player "respond" to the playing of a Chasm? I know a land normally can't be responded to, and I assume the same holds true for the Chasm, but I wanted to make sure that the replacement effect didn't open up an opportunity.

No.  Playing a land does not use the stack.  Neither do replacement effects.