saltwater is diffrent then fresh as long as you have 1-2 lbs of rock per gal of water (live rock acts as a form of bio filter) and skimmer (for a reef normaly 2x the water volume) that will be all the filtation you need. If you want to save some money on live rock you could get say 50 lbs of dry rock from macro rock or tbs and then 20 lbs of live rock from a local fish store or offline.
- as far as stock lionfish would eat clowns most likely
- wrasse's are fine just make sure your getting a type thats reef seaf some arnt.
- mandarin is not a fish id start a fresh tank with do some research on them they are hard to get to feed
- a tang would be fine in a 70 maby someone else will tune in on this but id stick to 1 for a 70
- normaly people dont put anenomes in tanks under a year old they can be hard to keep and need strong light also if the die in your tank there is a good chance they will kill everything
- clowns and flame angels are reef safe
- feather dusters arnt coral they are a kind of worm and do great in reef tanks
- as far as corals it really depends on what light you have for most of them starter corals are soft/zoas . as far as a light t5 and metal halide are most commenly use sometimes a mix of both you want to have 4 wats per gal so for you that 288.
fish need it;lights; food;Sponge has some good lights or you can look around at diffrent places