Were you planning on ordering the star from saltwaterfish.com? Linckia have very stubby arms that are nearly circular in cross section; common orange "Linckia" such as that sold be SWF have tapering arms, and are more likely something like Henricia or similar (it could be a Henricia?). They are closely related, but usually are a bit tougher than Linckia stars, except for Linckia multiflora, which is smaller and relatively tougher than other true Linckia. I would be very hesitant to put an orange Linkia in any tank under 75g with at least 100lbs of LR. Pristine water conditions are absolutely necessary, including a stable specific gravity in the 1.025-1.026 range.
Anyway,
The Linkia guildingi (orange linkia) is not a 'True' Linkia starfish. They are commonly known as the 'Orange Linkia,' (dispite that it's not a true linkia), or the 'False Linkia Starfish.' These starfish are much more hardy to keep in the home aquarium, and prove to be much easier to care for, compared to the Blue or Purple Linkia Starfish (linkia laevigata).
The exact food for the Linkia guildingi (or Henricia, if you plan on ordering on saltwaterfish.com) is unknown. We can only assume it eats films of algae, some species of sponges (Guessing Pineapple Sponges and encrusting sponges?), bacteria and possibly some species of pods. We can only guess that they do best in mature systems with high amounts of liverock; we can say that because the most success from these starfish comes from tanks which are mature with lots of liverock.
Remember,
All starfish have extremely sensitive hydrovacular systems, which are extremely sensitive to even the slightest change of pH, temperature, and salinity. Therefor, acclamation should exceed 4 hours (most people do 6-14 hours) using the drip method for aclamation. Otherwise, it may cause damage resulting in Loss of limbs, shrinking, and slowely dying (sometimes discribed as "Melting") off. Other methods of aclamation are often too quick and very stressful to the starfish.
Graham