Lionfish are poisonous so you do need to be careful when you put your hands in the tank to clean etc. It is not usually lethal unless you are alergic to bee stings and that sort of thing. Basicly they just make your hand swell up and hurt like a mother.
tank bred ocellaris clowns would be the best choice for a beginner, they are much harder to kill then wild caught ones and clowns are one of the hardier saltwater fish to begin with. Ocellaris clowns are also the "standard" clown that you always see in pics...the yellow and white ones. That is what I have and I personally like them better then almost all the other species even though they are so common, they are what got me into saltwater to begin with.
As far as the filter goes it depends on who you ask and what school of thought they use. I would say go with something semi-small just to do mechanical filtration and add water movement, then get a protein skimmer that is rated for up to 50-70 gallon tanks. With a tank that small you are going to want to do weekly water changes of about 10-15% so I wouldnt worry too much about the skimmer removing benificial mineral(though it will you are right)
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Adam
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