Hey, welcome to the site!
As far as cleaning it out, I would use some vinegar and a razor blade. The vinegar will remove any hard water spots/buildup. The razor blade will clean your glass up very nicely. Just rinse with warm water and some paper towels. Do not use any chemicals to clean the glass (windex etc).
Not sure as far as what do with the filters, not sure what you have either. The lights will be another topic I'm sure. Do you want a planted tank or just fish only? What kind of light fixture do you have? You said you had some dead corals so I'm assuming you had some higher light on the tank.
Again, welcome to the site!