I had one of these guys a few years back. Yes you can feed it krill, place a piece of krill close to is and it should move over ontop of it and start to eat.
If you keep them well fed they should not bother any corals but they might eat some small inverts if they can get them.
I did not fare well with mine for long, had it for a year and then it died. Starfish are not easy to maintain for any length of time in the home aquarium unless you have a big system that can meet their food requirements.
Good luck...
