The first pic is Fromia milleporella - don't even consider, IMO, in less than a 6 month old established reef with 100 lbs of LR. Most, IME, will die of acclimation shock or starvation. Again, don't let the small size fool you. The diet may be even more specialized than Linckia stars.
Success with seastars is measured in years, not months I'm afraid. Especially for Fromia, Linckia and relatives. Many will appear to be fine and be dying.
The second star is very different - it is highly predatory Red African star (Protoreaster linckii) and gets very large. It can be spot fed, and it will in time consume snails, corals, clams, scallops, etc.. It will get too large for a 12 gallon. Absolutely it needs to be fed.
