PLEASE ANSWER I want to start a 10-20 gallon saltwater tank with exotic sealife?

If you are reading this thank you. Since i can remember, I have been interested by sealife and now that I have developed good responsibility from other animals (one cat, one dog, and a 20 gallon freshwater tank with a lot of smaller fish and crabs and snails) I really feel ready to start my dream of owning and maintaining a small saltwater aquarium. Here is a list of things I would Like to include. separately of course, not all together unless that is safe for the fish oh yes, I must add that the animals need to have enough space to LIVE HEALTHY not have tons of free swim space just enough to not be cramped or unhealthy because I can buy rocks and such for them to hide in or other things such as live food or small jars for octopus to open to get food. Also, I do apologize for my misspellings I am about to head over to my local petstore for tank estimate costs and im really rushed and excited. Ok so here are the aquatic animals i would love to raise and let me again say that they are not all together I would take just one and care for it specially until I could upgrade to around 75 gallons. Octopus, shark, seahorse, eel, starfish, stingray, and clownfish (to keep them company if it wont cause harm to the clownfish or primary animal). Whichever one you have the most knowledge on is the one you should tell me about It needs to be reasonably priced also with cost ESTIMATES. Please tell me what it needs to live including tank size, other fish to keep it company, water tempurature, what it needs in the tank, how much I can expect to pay for it, how much for the filter, heater, lamp, liverock, food, and ANYTHING else it needs please tell me where I can buy it, what I need to take care of it, and how they are as pets. Please guys I am clueless right now and want to become educated of taking care of them I have already checked online and in books but they havent been specific good links would be greatly appreciated not like "petland.com" or something general please dont recommend a large bunch of starter fish that is a small purpose of the clownfish. I will give best answer to whoever can tell me the most about the animal from the above list and which ones i can and cant have in that sized tank also what the best and smallest breeds of them would be. so just write an answer an tell me all of this that you can and I will give you best answer and you can know that you have helped a stranger in a lifelong dream I willl remember you thanks any answer AT ALL would be greatly appreciated