As for Tatooine, people in the real world pronounce things differently all the time. Like how some people call New Orleans "Nawlins" and somehow Missouri becomes "Missour-uh."

The whatever it is at the end of ESB looks pretty and to me fits perfectly with the ending from a visual standpoint. I'm not too worried about what exactly it is, but the kind folks at http://www.astronomycast.com/ do Q&A podcasts occasionally and seem to love sci-fi movies so maybe someone should ask their opinion if it'll help clear anything up.