Twin Spot gobies are like mandarins...very hard to get to eat anything other than pods. They do best in an older tank and are very shy at first. They are spectacular looking in person..no pic Ive ever seen does them justice...just not the hardiest fish. They do much better in pairs, and will send sand flying. They are also known as signal gobys. They should be fine with your jawfish.

Star fish: Avoid brittle stars (they can be good little predators) and Im not sure but I think a sandsifting might actually be competition for the twin spots regarding food. Id get a 6 armed maroon star. They look like linkias (except the obvious 6th arm) but from out experience much hardier. I think Drs Foster has em in right now.

Id put some sort of algae (chyto) or something for you to help your pod population grow in the sump...a sort of makeshift refugium.

Basically, treat the twin spots like you would a mandarin.

Your basic reef shrimp should be fine with them (cleaner, fire, coral banded)
hth