I raise and lower that to match the height of the grain bed. It goes through the top of the cooler and I put a spring clamp on the outside of the lid to hold it at the correct level.

I kind of like how the recirc on a brew-magic system works. No sparge ring... it just uses a hose. Nice and simple. I posted a short video of it on my blog and how I modified my MLT to do the same thing...

Video and pictures...
Keg to Mash Tun Conversion with Recirc

Keep in mind, I just finished putting it together and haven't used it so I can't say how well it works yet. I'm expecting it to perform like the one in the video. We'll see...

i use a 3/4" copper tube with a cap on the end. i dremeled out slots that basically cut half way through the tube, and are a good 1/8" wide. it gets clogged a bit, but that just makes the spray diffuse more. i just sit it on top of the mash.

when i'm done i take the cap off (nothing's soldered, just dry fit) and clean it out with a bottle brush if i need to.

works great. i've done 15 minute mashes before. usually i just go for abotu ahalf hour and everyhting's well converted.

I have one of those pizza pans with lots of holes in it. I usually batch sparge so I only really use it when recirculating, but it seems to work good.