Repost: Am I prepared to get a fish and am I prepared to get a couple of fish?

I been saving up to get a new fish. I got a 50 gallon tank and a filter. And I might buy a heater for the fish tanks. I already set everything out. I also got this really cool fish house that's shaped like a sunken pirate ship ^.^, I bought those little live plants to put in the tank. I put the stuff on a large table where it isn't too bright or too dark, I'd call it dim or a little lighter than dim. I haven't bought any food yet but I lan to get it today. And which fish could I get? I don't want to get a fish that has too much room or not enough. Also, can a fish get lonely if I only get one? Also I was wondering what names [Yeah I really want to name them] that I picked out are cute, I'm thinking Sea turtle or Dolphin or Goat. Which ones I can't decide.Also I was wondering where is best to get a new fish? Thanks I'm a new soon-to-be fish owner. Thanks a lot ^.^