I have been thinking about how I might make a simple filled, carved cake, and am concerned about the amount of times it would go in and out of the freezer.

First I would put it in the freezer straight away, as I like the method where you wrap it up and freeze it immediately to seal in the moisture. Then I'd have to get it out, defrost it a little bit, and carve it. As I've never done it before, I imagine I'll be quite slow. I have read that working with frozen cakes is essential to the success of carving... true? If so, would I just keep popping it back into the freezer when it is too defrosted so that I can continue carving it?

Then I imagine I'd torte it, fill it, crumb coat it, and put it back in until I'm ready to decorate. (someone tell me if that's not right, I've never frozen a filled cake before, nor a crumb-coated one).

Is this in-and-out of the freezer going to ruin the cake? I work fulltime and have a baby, so doing everything in one sitting is not viable for me.

Frozen cakes usually stay frozen for a good period of time, and you definitely don't want to refreeze after crumb coating, so they'd only need to be frozen once. You want to level and torte your cakes after they've baked and cooled. Then you wrap and freeze them. Take them out when you're ready, fill and carve them. Then crumb coat. Cover and let them settle for at least 3 hours to overnight. Then you can put your finishing coat on or cover them in fondant, whichever process you prefer. Also, it helps greatly to only take out the cakes for 1 tier at a time.