Do you have a link for the tank or a name of the tank?
If you have shrimp in the tank then only get a couple of small hermit crabs. If you don't have shrimp, then 4-6 small hermit crabs.
Fairy wrasses can be common but it depends on the shop.
You can buy 4 Bangaii cardinals, but you might not get males and females. If you do get males and females you can build up the colony with the babies they produce. Or get 4 now and 4 later when you have a bit more money available.
Anthias are fussy eaters and most people try live brineshrimp. That can help but is not a suitable food on its own, they need more variety and rotifers are a good start. Copepods and mysis shrimp are also good foods. You won't get Anthias to take dry or floating foods.
Some species of dottyback (usually the bigger types) can be aggressive but bicolor dottybacks are peaceful and small.
The orchid dottyback (Pseudochromis fridmani) is a nice little fish and has a stunning colour. They are regularly bred in captivity.