If you can, request for captive bred seahorses at either Iwarna or Marine Life. Their contact information is found in the sponsor forum. CB seahorses have a higher survival rate as they will eat frozen mysis readily and they are less-likely to be affected by diseases common with WC seahorses. Avoid over-stocking if your tank is small, small seahorses will grow. I would suggest that you stick to 2 pcs. Only keep peaceful corals with seahorses, aggressive ones with strong stings (e.g anemones) should be avoided. There are many small skimmers on the market, the marine shops would be able to advise you more.