Yes, it's easiest to do it all in the esky. Mine is cylindrical but I won't go into why now.
What I use is very basic but very efficient. I have a reluctance to spend any more than needed
My copper pipe is just slotted with a hacksaw, and I have those slots facing up. Some insist they need to face down to avoid a stuck sparge, but have never had a problem with this. Here's an image
http://i40.photobucket.com/albums/e245/ ... 2_0347.jpg
And I don't use a tap, just some hose with a bulldog clip
http://i40.photobucket.com/albums/e245/ ... 2_0348.jpg
I think you'll be wasting your time trying to cool that volume in a bath of ice. It will take hours upon hours. Like Dogger says, I was cooling in a similar fashion, but it was in 2 smaller pots, not 1 big one. I got 10 metres of 1/2 inch annealed copper pipe and bent it to shape for an immersion chiller. It's expensive stuff now. $9.00 per metre
http://i40.photobucket.com/albums/e245/ ... 2_0356.jpg
There are other types of chillers, but I went with Doggers suggestion and decided on the immersion. Another method is to not chill at all. It's called, surprise, surprise, the "no-chill method"

With this method, you get a cube with lid from the hardware. The idea is to fill the cube until it is almost full with the hot wort. You then squeeze out the remaining air and put the lid on. Leave it sit overnight or longer, and then rack the then cooled wort off the trub and into the fermenter. For various reasons I don't think it's the best idea, but users of this method swear by it.
Here is a couple of pics of my set up in action. Like I say it's not anything fancy but works well.
http://i40.photobucket.com/albums/e245/ ... 2_0388.jpg
http://i40.photobucket.com/albums/e245/ ... 2_0392.jpg
http://i40.photobucket.com/albums/e245/ ... 2_0397.jpg
http://i40.photobucket.com/albums/e245/ ... 2_0399.jpg
If you get the opportunity to see an all grain brew in action before attempting the first one, it's a great help.
Cheers, Ed