Actually, the Blue Linkia (Linkia Laevigata) is the most difficult to keep.
The eaisest would most likely be the Linkia guildingi, which 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 in 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.
IMHO i would just go with a brittle or serpent star. They are easier to take are of, and wont melt when they die off.
All starfish appear to melt when dying from hydrovascular stress.
Take Care,
Graham