Freezing Cakes

I take mine out the night before and put them in the frig all day.   When I come home...I fill/crumb and put back in the frig overnight to let the fillings/crumb coat harden up.  The next day I ice/decorate.  

Can't answer about making it moist....I never put/need syrup in my cakes. 

I always freeze my left over butter cream and fillings.   Take them out the night before also and just store on the counter (unless filling needs refrigerated)  Some fillings like the mousse's that use heavy whipping cream don't always thaw out good but everything else does.

10 minutes after my cakes come out of the oven, they are wrapped in saran (from sams) and put in the freezer.  I put them on the cheapo cake boards so they don't get the grid markings from my freezer shelves. 

If you are getting lots of orders, the freezer can be your best friend!   LOL

I only do buttercream so not sure if things change with fondant.  I would take it out of the freezer the day before, uncover right before you work with it.  Or you can crumbcoat and fill while it is still frozen.  Lots of ways you can do it successfully.  You shouldn't need any syrups simply because you froze the cake.  I freeze my shortening/butter based icing with no problem.  I have successfully frozen individual cakes, and completely filled and decorated cakes (all white with the rose swirls over all).  Cupcakes also freeze well, both uniced and iced.

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.