I have to freeze since I have a full time job and I would never be able to do cakes without my freezer. Wrap each layer individually with plastic wrap, and put it in a freezer bag or wrap it with foil. I will generally pull the cake from the freezer a day or two before I decorate it. Leave it in the wrapper and thaw it on the counter. That way the condensation develops on the wrapper and not the cake. Depending on the size of the cake and the temperature in your kitchen, it should take a few hours to thaw.
If your usual cake recipe is moist then you shouldn't have to worry about adding syrups or anything like that. Just make sure you wrap it well to protect it from the freezer.
Yes you can freeze buttercream and certain fillings. Some fillings don't freeze well at all like custard-based ones or certain fruit fillings. But generally those can be prepared a few days in advance anyway.
Not sure what you mean about dividers and all that, but it is possible to fill and crumb-coat a cake and freeze it. It's also possible to freeze a fully decorated cake, as long as the filling freezes ok. What you have to do is put it in the box, wrap the box very very well with plastic wrap, and then again in foil. Same thing-let the cake thaw with the wrapper on.