I have another question. In dry fitting the threshold for a floating floor install, there is a gap of about 3/16 inch between the bottom portion of the threshold that would sit on the subfloor and the subloor. I think I should take care of this gap before permanently installing the threshold. What would be the best way to deal with the gap?

Rip a length of wood to 3/16" and glue it under that bottom leg. If it is going up against a vertical surface, it will be hidden.