So many questions, let me see if I can answer them. lol SPS
= Hard coral (small polyp) LPS
= Large polyp Softies could be anywhere from a leather to zooa's.
I usually temp float the bag in the sump or tank then dip them, after the dip they can go in. Deoending on the coral will dictate where you place it. Mushrooms on the bottom say and SPS
higher up your rock work. Most corals dont move, they stay where you put them unless a rogue hermit or snail moves them. lol Tank size doesnt actually dictate the coral but you wouldnt put a huge flowerpot coral in a small tank, they need room to stretch out and many corals have long tentacles that can and will sting other corals so you dont want them on top of one another.
keep a nice tank with good parmeters and light and the corals will get huge.
Most corals appreciate some food but in my experience its not a necessity as they get most of what they need from the light and when you feed the tank.
Can't say I've ever had a coral sting a fish but they do sting each other. I had a flowerpot frag fall face down on my palys and lost the flowerpot. :-(
Hope that all helps some.