What is the ideal temperature to cool the melted chocolate in a freezer?
Do not use a freezer, that's way too harsh on the chocolate and will almost certainly introduce terrible condensation, and possibly off tastes, if there is other food stored in the freezer. 

If you have a way to create a temperature-controlled "box", you should cool it at 20 degrees Celsius. If not, keep it in a room which is as close to 20 C as you can get, and on the dry side - most normal rooms will do, unless you live in a tropical or equatorian climate without air conditioning, you just won't get the most perfect shine if you keep your room much colder or warmer than that. 

"How long" cannot be answered, you just have to wait until it is solid through and through, which will depend on the thickness of your shapes. Just way overnight before trying the first one. 

Also see a diagram with best temperatures, which is slightly more complicated because it considers chocolate poured over a solid core, in this old answer of mine.