I currently have three in my tank. They have never moved more then a few inches, but you need to provide them with a rocky crevice to place their foot down in, as when threatened they will pull back into the rocks.
I feed mine cut up shrimp or scallop every third day or so, they are very aggressive feeders, and must have a good sting as the Skunk Cleaner shrimp get very ****ed off when trying to steal their food.
I have an SPS majority tank and have them down near the bottom of a 30" tank, you want them to have flow but not enough flow that they can't lay flat. They do not host clown fish.
When you get one they will attach very quickly and can be quite sticky when getting out of the bag. With my three they all attached to the rock work within minutes of being placed. I turned off my closed loop and mp40 so they wouldn't get blown around, and turned the flow back on once they anchored down. As with most anemones if you are one who is constantly changing your power heads flow patterns or messing with your lighting, they will wander, as long as conditions stay the same they will tend to stay put once they find their "happy" place.
A quick iphone photo from this morning
My rock flower garden by
MechEcub, on Flickr