you dont need a light on there unless there happen to be some corals. a nd in that case, they will probably survive okay if you jsut keep them in the sun
those buckets will work fine, that is, as long as you can find a place to put the salt. ahah
for temp, just keep them at a normal reef temp: 78-82*F
as far as powerhead placement, in a bucket, you can really put it anywhere because it is so small and circular that everywhere willg et flow
for your tank, as axtion suggested, you want there to try to be no dead spots. make sure that it is not in a strait circle though, this will create one huge dead spot right in the center. lol