get some rags, and i mean cotton rags, and a bunch of metal coat hangers. you can then twist a rag into a coat hanger and stick in the fuel gauge opening and some what wipe the bottom of the tank down.
you can also put in one gallon of gasoline and slosh it around then pump it out and trash it. just becareful of fumes going bang.
as for the smell use any cleaner you have but add a little orange cleaner to it. then leave some dryer sheets or coffee grinds in the area, to asorb the smell