Do your research, alas, re starfish: red/blue starfish will not live in ordinary tanks. THe knobbly kind will destroy many things you may want to keep. They are not benign. The black and white brittle star is about the only safe starfish that will live. Get online with your wife and work out a picture of the kind of tank you want, whether fish, or corals, or whatever. Having a 'destination image' in mind, one appropriate for your tank size, will let you tailor your community to what will survive together---will save you money and save the lives of specimens.
Once you do have specimens, be prepared with a ph meter, [reading should be 7.9-8.3], and an alkalinity test and buffer---reading should be 8.3-9.3. Keep those levels and your tank will prosper.
Just wait a couple more days to get that nitrate to 0. And when you do get inverts, use a refractometer to test their bag water and your water and be sure they match in salinity, at 1.024-6. They must be within .001 of each other, or the creature may die within days. Drip water slowly into the bag to adjust the bag water safely, and use your hand to transfer the creature into your tank---[wear medical glove if you're squeamish.] Do not let bag water touch your tank.
HTH.